The beauty of Christie is that he's telling Republicans exactly what a scumbag Trump is. While Christie doesn't have a chance at winning, he's doing a pretty good job of taking down Trump.
The cult base won't budge regardless of what truths are uncovered regarding Trump's grifting, lying, etc. But this does give Dems great ammo for the general election. They just need to use whatever Christie is dishing up now against Trump later.