Because if one could choose You Are Bound By Law (YABBL) to use with Let’s Keep Doing That (LKDT), wouldn’t the affected player just never get a real turn again besides drawing cards? Especially in a two person game, the unaffected player could just keep having infinite “full” turns if they wanted to as long as they didn’t do Rules Reset, Trash a New Rule, etc.
Our official ruling would be that you just can’t use YABBL with LKDT because YABBL does not function the way other Actions do (it is given out for a duration to penalize another player, rather than being like a more traditional Action which is truly a one-time, right-now function for the current player, so that it could simply be executed to completion by each player repeatedly on their turn). So yes, it cannot apply because of the reason you said.
The other card which we would flag as incompatible to use with LKDT is I’ll Be In My Bunk. It’s just not practical for multiple people to get up and leave the room.
In general, if there are multiple interpretations, and one works, and one doesn’t, you can bet we’re going to rule that the one that breaks the game is incorrect. But we understand that it’s nice to get official verification on these things.