We don't know if someone else would try to hold "Hakai", Zoro choose to do it for the sake of the others and he knew he couldn't do much despite trying, it's like it was explicit that anyone else would die doing that, thats when Law comes with "Shambles".
Obviously if we bring Zoro's previous defense capabilities to this, we can't even say if he would stay conscious or OK after King's divebomb beak attack for example, especially if you compare with how Zoro vs Kamazou went out. Raid Suit Sanji must be by far the most tankier Strawhat for now, we just didn't had a clue yet and im sure its yet to be shown even more crazy endurance feats. This is not Sanji's siblings in the Raid Suit, thats SANJI in the Raid Suit
For those who bring Page One blowing Sanji away and feeling "a bit of pain", to begin with Sanji wasn't even really trying, just a few basic kicks here and there, Luffy also clashed against Ulti and almost used Gear 4 and got blown away by her headbutt, after that Luffy realized he understimated P1 and Ulti, and yet he is tanking Kaido's special CoC infused attacks and coming back. Sanji got beaten freely by Black Maria, didn't used haki to defend himself, and got out of there like nothing happened, thats durability for me
Feeling pain is completely normal, Zoro felt pain even with Hawkins's nails, why wouldn't Sanji feel pain after getting blown away and hitting some buildings? The point of that was to show even these kinds of blows barely did enough to hurt RS Sanji.
On the other hand, i don't think Sanji can damage Kaido the way Enma Zoro can do, and obviously he wouldn't scar Kaido, also i don't know how Sanji would save Luffy from Kaido's mouth when he went out of Gear 4 cuz apparently Enma Zoro could damage Kaido, making him "spit" Luffy from his mouth.
Sanji's CoO and speed/overall mobility is probably the best in the crew with the Raid Suit, better than Gear 4 and it's limitless, he just didn't get 100% used to it yet, so there is a lot of possibilities for him to save people, would he try to hold "Hakai" and achieve it atleast for 1~2 seconds? Would he simply try to save some of them the fast as he could do just like when he needed to save Chiffon? Sanji's CoO would be enough to know "Hakai" was coming, just like Luffy did and warned the rest, giving Zoro a chance to get ready??
Lots of questions, and some of them are yet to be properly answered + more feats to sustain them