Putin probably made him an offer he could not refuse.....
As one who has spent a lot of time outside of the United States I've been amazed by how the Russian mafia permeates every aspect the international tourist industry. In order to build his world wide hotels the Trump organization undoubtedly has had extensive dealing with the Russian mafia.
The Russians make our mafia look like a bunch of boy scouts. They are ruthless, mortally efficient and an arm of Russian foreign policy with Putin as its head.
Trump would undoubtedly and reasonably, IMO, fear the Russian mafia far more than the "deep state" here....