Nah, you can't discus this in this cohort. They have their belief locked in, the fact is that Soy contains Phytoestrogens (plant oestrogen) which has no effect on mammals - where as cows milk is literally mammalian milk and therefore contains mammalian oestrogen and very much affects other mammals - such as humans.

There is a whole section on Nutrition Facts about this

https://nutritionfacts.org/?s=oestrogen

I will no doubt get abused for this but ¯\_(ツ)_/¯