I doubt they're in danger, WinUAE, WinAmp, WinAce, WinZip. Are they in danger? Nope. They denote the platform they're targeted at nothing more.
You cannot stop someone from writing a compatible product which is what AROS aims to achieve. It doesn't beg, borrow or steal anything from any of the Amiga OS versions it reimplements them from scratch.
AROS is safe and this is just the same FUD that MS likes to spread from their s***e cannon about Linux. Get people riled up and scare them off the project in question is the tactic and it's vomit worthy.
Andy