If we're going to talk about fight scenes and not hypothetical, I'll talk too. Doflamingo didn't even know haki in Marineford times. Nothing happened to Croc after he cut the Crocodile. Jozu took blood from an admiral. With his name attack, he made Crocodile vomit blood.

I would also like to remind you that Queen ate shit diff from Big Mom who doesn't use haki and fruit. Don't underestimate hurting the admiral.
Lol Doflamingo was Joking with Crocodile he didn't want to kill him.