And I think they would have said “you can use a bonus action to shove on your turn but after you do so you may take not do any other action than the attack action.” The timing is then clear and you don’t run into situations where you may not get to do the action that allows you to do the bonus action ( which is really the crux of the argument for why it only makes sense as a timing situation, you don’t have a bonus action to take until you’ve taken the attack action )
I could also say that since timing wasn't specifically stated, no timing is implied
Which really gets to the fundamental issue. For better or worse the rules were not written in a way to be analytically parsed. The rules were not written in gamer-speak with the syntactical correctness of a legal document.
Even [MENTION=6919838]5ekyu[/MENTION]'s "compromise" doesn't fit the latest version of sage advice. According to JC the action needs to be completed before the bonus action can happen. I don't know anyone that actually runs bonus actions that way across the board. If it works that way for Shield Master, it should work the same way for all bonus actions that don't specify timing.
In any case, I know how I'll run it because if you can't shove before an attack it's basically a pointless feat.