What he explained in his book is that he's an evil, dishonest person, who routinely lies and harms people in negotiations in order to get his way. I agree that being evil and dishonest is often quite effective - if you came up to me with a knife and an outlandish demand that I should give you my wallet, I'd probably concede the negotiation. But I don't at all understand the idea that I have to respect this as some kind of clever negotiating strategy. The innocent researchers whose grants he's cancelled are real people suffering real harm, and they don't become transmuted to a mere negotiating tactic just because Donald Trump doesn't care about them.