Reporters seem to have lost the art of reporting facts and instead think they can report motives.Which is exactly what you just did.
No, I gave my opinion. I carefully stated it as such. I can’t know motives as fact. I can only suspect.
It is one thing to suspect certain motives. It is another to act as a reporter of facts and state that so and so is doing this and that for X motive. Cruz could be focusing on Rubio because he is scared of a Rubio rise, because he has given up on catching Trump, or whatever. Frankly I think the simple answer is usually right. He is focusing on Rubio because Rubio is focusing on him. No one knows without asking Cruz. If the author wants to report on motive, ask the question and quote the candidate in context.