I wouldn't be so sure.
Spurs current midfield pivot is their weakest area; Sissoko, Wanyama, Dier, Winks and sometimes Erikson is pulled back. So I'd say Tielemans would be an upgrade on everyone bar Erikson, but who isn't naturally a deep player.As for ManU, they are losing Ander Herrera and possibly Pogba whilst Matic is aging. That would leave them with McTominay, Fred and Pereira. Clearly they are going to want to rebuild their midfield.
Tielemans is young, unfavoured at his club and now has proven himself in this country. I think he would probably go straight into either side.