The England defender came under criticism by the former Manchester United captain for celebrating by appearing to shun his critics by putting his hands to his ears during the 5-0 rout of Albania.
Keane was scathing at Wembley, suggesting Maguire's indifferent early form cannot be excused by one goal in a five-goal rout.
"He thinks he's shutting the critics up, but I think it's embarrassing," Keane said on ITV.
"He's been a disgrace the last couple months for Man United. He thinks if he scores there, he's going to shut his critics up.
"Embarrassing."
However, the England boss was more than happy with what he saw from the 28-year-old as he scored his sixth goal for his country - the same as John Terry and Jack Charlton.
"Well he is a fantastic footballer," Southgate said. "He's been such an important part of what we have done over the last four years.
"So he is consistently scoring those set-piece goals for us now.
"His all round game is good, solid, strong and he will have enjoyed that tonight."