people can SDI out of pkfire anyways, so it really depends.
On bowser, maybe even more times than that.
on people who can't SDI well, sure, but make sure they stay trapped in the 2nd pkfire and you can hit them with the bat if they do get far enough out of range.
on people who can SDI well, go with something you know will hit, because they will likely perfect shield or jump away.
It all depends on your opponent's actions though.
one useful, semi-true combo is to get someone trapped in the pkfire wall, sh dair them then immediately utilt them as you hit the ground. the dair auto cancels if you start the dair early enough, so you don't really undergo much ending lag at all. once i found this combo, i said, "forget the unreliable dthrow>fair, this can almost hit all the time!" if they tech, you're in trouble, if they di out of the pkfire wall, you can still get them with it, but they have to have just gotten out and your dair hitbox is basically already coming out. if they get up or roll, which they havent against the players i've done it on, then you have to follow up with something else (getup attack = shieldgrab or shield usmash; getup = wait then do an attack; roll = either dash attack or dash grab, depending on how far the person rolls, and if they roll slowly, maybe another pkfire). i like this move so much! its worked several times.