Actually, after reading the transcript he is right. Either Trump feels pressure from Cruz and is reaching out for the Indie, Moderate and Dem vote (open primary), or he’s looking for to score a YUGE victory to give the air of inevitability (a little early for that, though).
It could be he’s trying to incorporate democrat blue collar voters into his base.
The old Reagan coalition included blue collar democrats. They are more libertarian now than then in many things, but they are protective of jobs and industries in America that provide jobs.
Rush did eventually say he would support the Republican nominee.