Good points, but Rob doesn't care about that and he just loves to compete against anyone the UFC put in front of him.
Even if the second fight against Izzy was close, the reality is Whittaker is 0-2 against him.
He's still hunting for that belt and unlike other top contenders he won't just sit on the sidelines waiting for another TS if that means he'll have to wait for when the champion is ready.
Prime example of this is him accepting the first Costa matchup back in 2021(Costa did withdraw from that bout and Gastelum stepped in) after he just defeated Till and Cannonier, Whittaker already had another TS locked in however he chose to keep fighting while Izzy was up at LHW.
Back to this potential Whittaker/Costa fight tho, I do think Rob needs another solid one or two more wins if want another crack at Izzy and he hasn't fought Costa yet.
Him being active and beating anyone the UFC give him is the fastest/best way to do it too.
Another thing that this fight brings is the narrative that Rob beats him and Izzy's common opponents in better fashion(partly true IMO). Izzy TKO'ing Costa is arguably his best performance so let's if Whittaker can do it just as good or better.