If you can see Bayo is coming into land, then yes, grab is the safer option.
I'm reffering to when she's already landed on stage, with the landing lag, and players just go for grabs instinctively.
I know as a Marth player that I'd mostly go for a Dancing Blade over a grab past low percent, especially if near the ledge.
the thing is, once you've realised she didn't witchtime it might be too late to react with anything else already.
you also have to watch out when she lands because she has many mixups like fairs, dair, witchtime (she moves away and stalls in the air), or she's landing with a downwards sideb where it's hard to even react to it & predict the exact position you need to be in and then she can't hit your shield otherwise she'll jump up again and you likely have to shield or make a defensive move otherwise the landing hit of that will hit you, which is limiting the punish options even more.
witchtime might not decide games all the time, but it's sheer existance is why you'll have to get 50:50s right all the time. it's pretty difficult to punish even if you expect it and if you guess wrong and she just attacks you you might already be in a huge combo string of her.
bayo players have already gotten used to being able to mix up their landing and they're doing it very well. just going to the ledge, mixing you up into believing they're going to land and punishing you (dair and kill instead of you getting a punish on their landing) or just moving around 3 times more until they finally land somewhere.
and the threat of witchtime will also keep you from just trying to hit her somehow because if she guesses right you might die starting at like 70+ or maybe just get death combo'd no matter the %s.
i agree that sometimes it might be possible to punish differently in time. i still have to work on that myself, but it's not always possible and you don't want to miss such crucial punishes by attacking too late if you've at least could've gotten a grab.