I think the parent is saying that the only value add for Nvidia to purchase ARM itself rather than just purchasing an architectural licence is to use ARM in an anticompetitive way.
I think that's the big irony here. It's taken ARM decades to break out of embedded/mobile and get to the point where they're seriously considered for workstation or server use. If Nvidia were to acquire ARM it would likely antagonize everyone to the point where they'd rush back to x86 and Nvidia would gain nothing.
It's enough for a short term gains, which is enough for a nifty bonus to a CEO.
If so Nvidia will surely buy ARM.