The Belgium international netted his 14th goal of the season as United bounced back from the Manchester derby defeat at the weekend.
The three points were also vitally important in keeping the Red Devils second in the table, 11 points behind Man City.
Lukaku waved at the home supporters after hitting the back of the net – sparking outrage on social media.
The 24-year-old is going through a barren run of form and has taken some tough criticism for his performances.
So Neville thinks he was just hitting back at the haters and trying to prove a point.
“The whole stadium hardly celebrated his goal,” Neville told Sky Sports’ The Debate show.
“I think there was a massive hangover from Sunday.
“I think there was disappointment from Romelu, who had a disappointing game.
“He was involved in the City goals and the chance he had at the end, so he did suffer a lot of criticism.
“Maybe it wasn’t a night to celebrate.
“With what happened on Sunday it was perhaps not the right moment to celebrate.
“That hit Man Utd really hard on Sunday and there was a flatness around Old Trafford (against Bournemouth).”
Fellow pundit Mathew Upson was also disappointed with the forward’s actions.
“I think he has had a lot of criticism, he has had a dry period in terms of goals,” he said.
“Over the season you look at him he has been very good.
“But behaving in that way draws attention to him more.”