Bush wasn't the sitting president at that time, may not have even started his run when the book came out.
Trump was one of dozens that had publicly stated he was planning on making a run for president.
Which recent POTUS does this remind you of?
"Choose your leaders with wisdom and forethought.
"To be led by a coward is to be controlled by all that the coward fears.
To be led by a fool is to be led by the opportunists who control the fool.
"To be led by a thief is to offer up your most precious treasures to be stolen.
"To be led by a liar is to ask to be told lies.
"To be led by a tyrant is to sell yourself and those you love into slavery."
Octavia Butler on How (Not) to Choose Our Leaders