You think after what Jinbei did to Big Mom, and the humiliation that was done on her by the Strawhats as a whole, that she'd even give Jinbei a shot at her wheel? And then just... let him go alive?
TBH I think that would make her far more of a joke than Jinbei simply getting the better of her at sea.
Even if not killing Jinbe could've been the more advantageous choice? I don't think Lilin is that unreasonable. I've already voiced my opinion on this in the spoiler thread, but I'll re-iterate. Jinbe has a very powerful soul, a soul strong enough to defy even Lilin's soul pocus, as such it has a lot of value. If Lilin kills Jinbe and all of the sun pirates, she gets her revenge, but she loses out on Jinbe's soul which is good and all but if Jinbe willing offers up his soul in exchange for the lives of his comrades I think Lilin would've considered it. Moreover, with Lilin, I think you always have a choice or rather her abilities just seem to work that way. Even in the last scene we saw of Lilin on WCI, she said "Life" or "Death" implying that all of her targets had one of two choices, "give in" or "die where they stand". Like I said, I don't think the notion of Jinbe having escaped by himself shames the BM pirates. However, if all of the fishmen and Jinbe were able to escape/leave WCI without bearing any consequences then that is a massive L for Lilin and her pirates imo.
Lastly, in a situation where she took Jinbe's lifespan in exchange for him leaving WCI, not only would she have Jinbe's soul but she'd have also doomed him to a untimely death. Jinbe's already far gone in age so imagine if he lost 50 years. I personally doing that is a lot more favorable for Lilin than simply killing Jinbe off.
Because they were delaying the fleet from getting the Sunny, which couldn't escape. Jinbei then stayed behind because with him in charge he would be able to stop any of the Sun Pirates dying, whereas without his strength it was meant to be a suicide mission.
As capable as I think Jinbe is on the seas, the bolded bit a bit too ridiculous for me to believe. Putting aside the fact that you think Jinbe alone could've stood against Lilin's fleets without bearing any loses, you honestly think he'd have been capable of doing that with Lilin in hot pursuit? Also Jinbe's time of arrival simply doesn't make sense if that was indeed how things panned out.