Telling ya'll, this is unfortunately the standard every arc. Oda would rather give Luffy a 2v1 against these 2 enemies (i.e. why the Robot probably exists...) than give Kizaru to anyone else. This is why Lucci is fighting Zoro somewhere completely different and why Sanji is now placed at a massive disadvantage between 2 major entities (he will probably lose or be pushed to the side for a VA)
Just think back to WCI where Oda didnt have Sanji fight anyone signficant yet had Luffy defeat 2 of BMs YCs. There is a threshold where Luffy surpasses a certain level of enemy before his subordinates do the same.
This is why even post-Kizaru, you still have Akainu and the remaining Admirals to fit that mold. Its like the people who couldnt believe Luffy would eventually solo Kaido when everyone got kicked off the roof, it was HIS battle to win.
Now we have an Admiral and Gorosei, the same logic applies. Either he fights one of them and the other survives, or he fights both and they lose. This is essentially the status quo.
Everyone will hate this comment, but Im just trying to lay out some truths and patterns that already exist in this series with Luffy. The Robot seems entirely central and logical to helping Luffy fend off more than one person while in Gear 5. In fact, it even seems like the Robot went to Mariejois to potentially eliminate them if you think about why it was there destroying Mariejoa