I think Cruz plays fast n loose on immigration. He might have been somewhat against immigration before Trump. I doubt Cruz was very anti-immigration when he was running for the senate. He teamed up with Beck to give out stuffed animals to children crossing the border illegally. So he’s trying to have it both ways.
Trump was unequivocally against amnesty and building a border. Cruz waited to see how that went over before he began chiming in.
Makes sense to me.