If you mess this up you either don't grab ledge or just straight up die [maybe it's PM only but I saw a Link player overshoot the ledge XD]. It's also super laggy, whereas Bowser's up+B is actually pretty low on endlag.
I don't do this much because I either will just grab ledge and punish onstage landings if it would kill [vs say Sheik, Marth, and Falcon], or because I'd rather watch them die. Sure it looks cool, but if grabbing ledge is what I need, I'd rather just line up for that over missing and now being stuck in an 80 frame animation [or whatever it is].
I think it has potential for edgeguarding spacies [you grab ledge to prepare to cover the up+B while doing this to cover a side+b - if timed well, they get hit if they side+b but you still have plenty of time to get off the ledge to cover their up+b], but that's pretty situational in my opinion, and I'd rather just read their option by covering side+b with rang or bomb and preparing to either followup after rang/bomb connects [if things go well] or get ready to nair/dair/up+b the Fire Fox/Fire Bird.