You read the site correctly, it's just that the information on the page is incorrect.
Commercial cream production consists of 5 main steps (from here, lots of info about different types of cream there too):
- Skimming, centrifugation: separation of fat globules in milk. Milk skimming is done in a centrifugal cream separator.
- Fat standardisation: in order to obtain the expected fat content.
- Homogenisation: to prevent the creaming phenomenon during storage and to allow an increase in cream viscosity (for low-fat fluid creams)
- Heat treatment: the objective is to inactivate microbial lipases and as a result destroy pathogenic germs without damaging the cream organoleptic qualities. Most creams are pasteurised.
- Seeding and maturation: pasteurised creams may be matured with acidifying, aromatic or even thickening mesophilic lactic bacteria. Maturation gives more taste to the creams and protects it against lactic acid and bacteriocin production.
Gelatin would make a poor filter for this sort of thing - it is weak structurally and diffusion of the water molecules through the pores is slow - it would take days to dialyze/strain the volumes produced in a commercial system, which increases the risk of bacterial and fungal contaminants growing, and makes the system slow.
Gelatin is added to some creams (thickened cream (UK/AUS/NZ), whipping cream (USA)), to act as a thickener and produce a smooth stabilized foam when whipped. Gelatin can come from a variety of animal sources, but generally pigs and cattle which is why creams need to be certified as halal. Many commercial products contain vegetable derived thickeners (e.g. carrageenan) instead of gelatin