"This guy is going to provide an opportunity for a whole bunch of athletes to speak up" in support of Collins and of playing with teammates who are gay, Sims said.
Advocates say Collins' announcement, which was largely greeted with public support, has opened the door for other athletes in major U.S. team sports to come out.
"Just like in every other field, we'll also see others that follow," said Malcolm Lazin, executive director of Equality Forum, a Philadelphia nonprofit that promotes education on gay rights.
"We're very excited to have a really visible role model," said Anna Aagenes, executive director of GO! (Generation Out) Athletes, a nonprofit organization focused on supporting student athletes who are lesbian, gay, bisexual, or transgender.
Aagenes, who works for Sims in his Center City office, spoke as she was on her way to be interviewed by a TV station in York, Pa.
"I've been pretty astounded by how quickly things have progressed in recent years," said Aagenes, 24, who was a track and field athlete at the University of Pennsylvania and attended Central Bucks High School West.
Sims said the Collins announcement was "long overdue."
Female professional athletes have been coming out for decades, and high school and college athletes of both sexes have become increasingly open about their sexual orientation, Sims said.
The NBA, NFL, NHL, and Major League Baseball have been the last high-profile holdouts among active players.
Sims predicted a large showing of acceptance for Collins and other male professional athletes who come out.
He likened the situation in professional sports to his new arena in state politics.
Sims may have been the first out candidate to win a House seat, but "there have been gay members of the Pennsylvania legislature for 225 years of its history," he said.
Contact Robert Moran at 215-854-5983 or firstname.lastname@example.org, or follow @RobertMoran215 on Twitter.