If Lambda's 4B had no hitstop on the first hit, then the 2nd hit--the actual overhead--would be a 17 frame overhead.
If it has the theoretical 20 frames of hitstop on the first hit, it is then a 37 frame overhead, effectively.
All anyone is saying is that 37 frames is PLENTY of time to react to the fact that it's an overhead vs. 17. Obviously it's not actually 20 frames, but it's enough in CS right now that it is not difficult to react to.
If they made the hitstop bigger, it's a nerf. End. Hit stop has no bearing on whether or not you get to "do anything" and I have no clue where that idea even came up, but it's complete nonsense.