Cruz is the one who is conducting the "scorched earth" battle.
I would bet money he knows what was done in Wisconsin to keep him in the race.
It tells me something about the man that he wouldn't put his country before his ambitions. History is filled with little men like him.
As far as I can tell, Cruz is following election law, and paying attention to the details of each state to maximize his rather slim changes. As a bonus, he is keeping Kasich from rising, which makes it much harder for the establishment to nominate Kasich. Trump would be best off with both Cruz and Kasich out of the race, but that won't happen. If Kasich stays, it's best for Cruz to stay too (I have analyzed a fairly large number of elections, and a three-candidate race is the next best thing to being the only one left). I'll vote for Trump - happily - but I certainly won't condemn Cruz for staying in or for trying for delegates.