Looks like another Bush is trying to position himself for a White House run and thinks he can recruit the Trumpsters into supporting him by feigning support for Trump. Will it work? Probably, since, in their minds, anyone who supports Trump is good (even if it is completely fake) and anyone who doesn't is bad.
Personally, in my mind, little Bush is a disloyal, dishonorable, opportunistic punk to give Trump any kind of public support after the lies he told about his uncle. I wouldn't trust him as far as I could throw him.