The 18-year-old has been granted a work permit to move to Old Trafford, which puts the finishing touches on a £3.5m deal.
Carvallo believes that the striker would have been better off staying with Universidad de Chile, stating that regular first-team football is hard to come by in the European leagues.
"Angelo Henriquez won't get many opportunities at Manchester United," said Carvallo. "It would have been better for him to continue growing at Universidad.
"It's an advantage to have players in Europe, but the acceleration of their growth process does suffer.
"In Chile a lot of them were regulars for their teams, but over there they aren't really under consideration."
Henriquez, an Under-23 international, has yet to make his senior debut for Chile.