User blog comment:Neowitch/706 - Be Prepared/@comment-79.107.224.240-20130422171756/@comment-4493594-20130422180149

It's because that's how Doflamingo punishes subordinates who disappointed him the way Bellamy did. And the latter was fully aware of that. In fact, I believe he didn't expect anything less from his boss.

Now, if Doflamingo wanted to kill Bellamy, that would be a different story. But while his words back then did sound like he wanted Bellamy dead, Doflamingo merely told him that he is no longer a part of the organization. He even told him to do with his life whatever he wanted before saying that he didn't need him anymore, which clearly indicates that Doflamingo had no intention to kill Bellamy from the beginning.

So, yeah, considering what Douchefabmingo is capable of, he was pretty merciful towards Bellamy. Which is why Bellamy's loyalty doesn't come to me as a surprise.