The England international was given a formal warning by his club after offering a defence for Australia international Folau, who sparked outrage with an Instagram post that said "hell awaits" drunks, homosexuals, adulterers, liars, fornicators, thieves, atheists and idolaters.
Vunipola has been booed by some fans during his appearances for Sarries since the controversy, although the criticism from the crowd did not seem to affect him on Sunday (AEST).
The number eight scored a second-half try and went on to be named man of the match at the end of his team's 32-16 triumph at Ricoh Arena.
"Behind closed doors, I've felt a lot of love, a lot of kindness towards me," Vunipola said.
"I'm very grateful to be part of this team. Hopefully we can keep it going, keep up what we are doing an enjoy every minute of it."
Asked specifically about the booing heard during the game, he replied: "From my point of view, I believe in what I believe in. There was no intention to hurt anyone. That was never my intention.
"I'm just grateful to be able to play, to be fit."
Boosted by the return of Brad Barritt and Mako Vunipola from ankle injuries, Sarries booked a fourth European Champions Cup final appearance in six seasons.
Owen Farrell kicked 22 points and was on target with the conversion attempts after tries from Michael Rhodes and Billy Vunipola, who praised the spirit within the squad.
"It's more than just a rugby team. I'm thankful that I'm playing for them," he said.
"I think we were somewhere close to our best. There were probably a few boys there who were not as fit as they would like to be, my brother Mako and Brad, but everyone stepped up.
"That's part of the journey — fighting as hard as you can to be involved in these kinds of games."