Yes, he wanted to hide his identity. What I meant is he allowed himself to be hit the way he did because he wanted to take the full power from P1 and see how much it would impact the suit. Sanji doesn't even offer a good block, just extends his leg hald-assedly. If you don't exert any real counter-force in this position you just have bad stability and can easily be chucked away
Similar where Daifuku overpowered Sanji but thats because Sanji and the crew were ganged up from all directions Sanji was busy looking around gauging the situation, so Daifuku could overpower him from that bad stance he was in when he isn't actively offering counter resistance
Sanji clashed with the biggest genie, but was chucked away from the exact same position that P1 chucked Sanji away from. Again, same position in both instances...
Moments before Sanji had just called P1 weak: "I can quickly take care of this idiot". Sanji would defeat P1 in base without much issue