Does dry frying tofu really cause tofu to better soak up a marinade?
Marinated tofu is essentially a myth perpetrated by well-meaning people who are, in my experience, culturally pretty far removed from cuisines where tofu is heavily used. Tofu is not especially porous, because it's texturally very similar to a custard. Maybe osmotic pressure will result in a little flavor transfer to a custard, but it's not the most efficient way to do it. Marinades are pretty rarely used for tofu in Asia in my experience.
You're more likely to see pan sauces or dipping sauces, or occasionally a topping added after cooking. But people in Japan, China, and Korea will generally expect a much fresher, beanier tasting tofu than you're likely to find in a US supermarket, so there's not as much of an impulse to cover up the flavor. In the US, thanks to generous expiration dates and a fairly unpicky customer base, a lot of tofu sold in supermarkets is slightly soured and just doesn't taste very good.
The primary effect of the dry frying technique on the page that you linked to will be to create a bunch of nooks and crannies and irregularities at the surface of the tofu that will make more of the sauce stick to the surface of the tofu, and the reduced water content will make it less likely for the tofu to break apart. The higher surface area may contribute to the perception of more flavor because you'll have more of whatever salty solution you've seasoned it with on your tongue. But inside the tofu you won't really get much additional flavor.
Freeze-dried tofu removes most of the water from tofu and small holes form where water had previously been. When rehydrated and squeezed, you'll be able to get a lot of a marinade to enter the tofu because there's plenty of ways to get in there. The side effect is that the texture will be completely transformed into a sort of spongy mass, which can be pleasant on occasion but eventually gets a little tedious, so freeze-dried tofu is eaten only rarely and in small quantities in Japan and most of China. It's frequently seen in lamb hot pots in China and occasionally in rustic simmered dishes in Japan. You can come close to the texture by actually freezing your tofu and then pouring boiling water over it a few times, but I usually just buy it from my local Japanese market.
One form of marinated tofu sometimes seen in China involves very aggressively pressed/weighted tofu that's been pushed between a muslin-like cloth for an extended period to drain. It's often soaked or cooked in a soy and sugar solution with various spices, but most of the flavor and color is concentrated near the surface; only some of the salt really seems to get to the center of that, so it's often made in fairly thin blocks.
I've seen patted and pan-fried tofu used in Korea and occasionally in Japan, but it was typically not marinated; it was typically cooked in a little oil until lightly browned and served with a dipping sauce of freshly-grated ginger and soy sauce.
Deep-fried tofu also creates more surface area for sauces, especially if dusted with a starch like katakuriko or cornstarch, but it's also generally only an occasional indulgence in Japan, China, and Korea, and also mostly affects capturing flavor that touches the surface of the tofu. (I'm less knowledgable about food as served in Southeast Asia, including Vietnam and Thailand, so I can't speak as authoritatively for all countries with a long history of serving tofu).
I don't know if it works well, but a Japanese TV show suggested that you can soak tofu in salted water to reduce the tendency for soft tofu to fall apart when stir-frying or braising. I haven't seen enough of a difference to justify regularly applying this technique and I haven't done a side-by-side comparison to be sure that it actually has much of an impact. But based on the guidance from that show, I suspect that if the marinade has any effect on structural integrity of the tofu, it's due to salt and osmotic pressure.
Pretty much anything that removes a substantial amount of water from tofu will help it soak up marinades and sauces. Both are essentially flavorful water, and if the tofu is already full of water, the flavor has to very, very slowly diffuse into the tofu, while if the tofu has been dried out somewhat, the sauce or marinade can simply soak directly in. Dry frying is one method for getting a lot of water out; baking is also pretty effective.
Pressing the tofu is also a good idea: place slices between two flat things with a decent amount of weight on top, tilt it so the water can drain, and leave it for a bit. It's an easy way to get some water out of it; it'll make any subsequent cooking step easier by reducing the amount of time the tofu boils and steams as the water escapes. And it does make some room for flavor to work its way in, though of course not nearly as much as mostly drying out the tofu by baking or dry-frying.
As for your request for empirical evidence... just try it. It's an extremely obvious difference.
It seems so.
In this recipe the tofu is dry fried slowly in order for the water to evaporate. According to the recipe, the removal of the water facilitates both browning and soaking of a liquid after frying.