@ShinmenTakezo
The main reason Sanji faced P1 in the first place was to prevent the town & it's people from getting hurt as a result of P1 rampage, so he donned the RS in order to 1.) hide his identity and 2.) see if it could actually provide him with additional strength to aid him in protecting his comrades given they are facing off against a friggin Yonkou. The bit about him taking out one of Kaidou's forces was a just an added bonus, and not the main reason he engaged P1 in the first place nor the main reason he wore the suit.
P1 is an ancient Zoan so if Sanji didn't kill him, chances are that he could've recovered somewhat by the Onigashima raid but still if Sanji was able to weaken P1 for the raid on Onigashima, he'd have also fulfilled that objective. I personally don't think we'll be seeing P1 on Onigashima tho but we'll see in the next few chapters.