[...cozied up to him some way(threatened) and he eased off on them.]
Are you suggesting blackmail?
“Extortion of money or something else of value from a person by the threat of exposing a criminal act or discreditable information.” (Yahoo dictionary for blackmail).
“threatened” may have been a little harsh. In the example about the reporter, it may have been on the order of “do you value your journalistic career?” kind of statement. Sort of what they did to GQ mag to spike a story. Don’t recall the book defining what may have been suggested.
In ref to the Bush thought, I think BJ just used what, everyone admits, is a very strong and likable personality. I think it is quite likely that if one likes a person they may be less likely to offend them. Plus 41 and 43 respect the institution of the Presidency more than BJ and spouse.