My goto for distrust of MS https://en.m.wikipedia.org/wiki/Embrace,_extend,_and_extinguish
There's not a single reference on that page that's less than 20 years old. Yes, Microsoft did some anticompetitive stuff back when Bill Gates was CEO, but it's absurd to suggest that that still "informs what their future actions are likely to be". A lot has changed since the 1990s.
It's not just preferring FOSS, though – it's as if people have to publicly perform their hatred of Microsoft.