More likely it was Jeb. He and his supporters are getting shrill and desperate.
How much time and money did Jeb! spend to take Rubio out? I’m guessing millions; and Christie did it in under a minute.
That would make sense from a rational, mutual self-interest point of view.
But it's hard to imagine Jeb and Chris as buddies, pals, or allies or partners in crime, and to easy to suppose that they really hate each other.
I think Christie was just making one last desperate attack to give his campaign a last chance at surviving.