If you strip out his autism, his argument is basically just that microsoft will have an excuse to sue them into the ground if they look at the code. The thing is, though, that microsoft can just sue them into the ground anyway. They always could. It doesn't really matter if microsoft has an argument to leverage against them, they can just keep throwing lawyers and false lawsuits at the problem until it goes away. At least, they could if they gave a shit. This whole thing with the leaked source code would give microsoft a somewhat more solid footing to argue against reactos but they're morons if they think that following the rules like good boys will ensure that microsoft will play by the rules also. For one thing, unless they have some more formal and legally defensible way to verify that nobody has seen the code other than 'we ban people from our fbi.gov when we find out they've seen it, your honor', microsoft can just accuse them of it anyway.
I've seen this before with other somewhat legally grey projects who think that if they just follow the rules hard enough, then they can avoid big daddy corporation noticing and then skullfucking them. Basic measures like staying anonymous and mass decentralized distribution never seem to occur to them.