It seems similar to the parallel of iOS builds where its been possible to do so with virtualized MacOS on non-Mac hardware for a long time but its a violation of the TOS of MacOS to do so. Apple does spend effort ensuring that companies running cloud builds do so on Mac hardware; they don't care that the true end user is running Windows and achieving an iOS build as long as there was Mac hardware doing the actual building.
So this reply is along the lines of "we did something for 3 years that allow and they never stopped us" which isn't very strong evidence they won't stop you now that you're doing something they don't allow.
They may not do anything here thanks to the current EU climate though, I only mean that the fact they did nothing about Beeper Cloud is not evidence one way or the other.