Last night around 10:30pm, I put a frozen chicken thighs, vacuum packed in a pot of cold water to defrost. I intended to put the whole pot in the fridge before going up to bed. Unfortunately, I dozed off in front of the TV, forgot about the chicken & went up to bed. This morning I remembered as soon as I opened my eyes. I called my spouse who goes downstairs every morning around 3:35am, to ask if he noticed the pot w/the chicken, he said he did, & put the whole pot in the fridge. He said her checked, chicken was still ice cold & no odor. I went downstairs to check myself, he’s right, but I’m still nervous about using the chicken, it sat in water 4.5 hours. I feel I need to discard this pack & just defrost a new pack. Am I right, or just being wasteful.
It sounds like you weren't using running water, which guarantees that the water the chicken would be sitting in stays at a constant temperature. Since you had left it in a standing pot of cold water, the temperature of that water probably got up to 50 or 60 degrees, depending on how cool you keep your house, which is most definitely within the danger-zone. Your chicken was not thawed safely.
That does not necessarily mean that it was contaminated, but rather that it had the opportunity to become contaminated.
Personally, I think you'll be fine, because your husband caught it before it was out for too long, but 4.5 hours is certainly pushing it. As long as you cook it properly to at least 165 degrees, the chances of you getting food poisoning are pretty slim.
Also, for future reference, if you are going to quick defrost chicken in water, you should only be doing so when you plan on immediately cooking it, rather than throwing it back in the fridge. See here.