Jinbei staying behind and sacrificing himself (together with Germa and the other Sun pirates) in order to let the SHs escape has been a major plot point of WCI.
It's not about the way Oda could justify an escape.
It's that there was such a seemingly convenient way out in the first place, which doesn't fit the "Jinbei sacrifices himself" theme at all.
Here he stands, smiling and in perfect health condition. Appearing out of nowhere in just the right moment.
This massively downgrades the entire ending of WCI by default. It also lowers the stakes - which weren't feeling that high to begin with - even more, since nobody even feels the slightest threat anymore. It has really become a "happy, go lucky" type of adventure, where you just know there will be no consequences for the main characters and their closest friends.