Girgensons probably won't be playing this year and maybe not even next year. His style would seem to lend itself to playing a 3rd line role early in his career anyhow. This is best case scenario for Buffalo in a lot of ways.
Is there some drawback to TT that is scaring teams away?
Not sure. There was a Finnish poster on the prospects forum who thinks he's a joke and has no chance of succeeding. IIRC he basically described him as a quintessential Euro who will have a hard time in North America.