Bloomberg is big money, corporate type. Sure he's socially liberal but he's also very fiscally conservative. Establishment/Rockerfeller Republicans, Wall Street types, plutocrats, Grover Norquist anti-taxers will flock to him instead of the pseudo-populist Trump.
Face it, he'll cut into both candidates, just not evenly.
He's not fiscally conservative. He's staunchly pro-minimum wage increases, pro-Obamacare, pro-environmental regulations, etc. He's fiscally centrist/center-left.
Although I hate Bloomberg, I'm glad we have at least one Bloombot here. Diversity is a good thing.