right, i think the whole relation of ace-tama needs to make more points in the story, and not only to deepen luffy's bond with tama... we still can't say that's a plothole until the whole story is covered tho, at least till the end of this arc... remember that this arc is the very first arc that somehow got time-travel related thing in one piece, so imo at this point, anything could happen
ps : i would be pissed if there's actually nothing more point in ace-tama relation and tbh i think i would start to kinda doubt oda-sensei's writing skills (is he really miss ace so much that he would show him in the middle of the story out of nowhere with a really insignificant role??)