Thanks, it’s been added to our bug tracking to fix this issue.
As for the intent of the _Validate code, it is as you understand it. I don’t disagree that it may be a little harsh, and it is possible through a bug in the game for invalid parameters to be passed in RPC. You can always return true regardless.
It’s a new feature that we’ve added in UE4 and as we try to use our own features, and get feedback from others, we’ll see if it needs improvement or possible redesign.