I don't believe any rec league affiliated with SCYSA can have players who are also registered on SCYSA select teams for the current seasonal year. This would probably not be the case with AYSO or YMCA rec leagues.
My daughter played for a couple of years in a local county-related, non-SCYSA-affiliated rec soccer program which would not allow select (club, classic, etc) players to participate. They instituted that rule because the rec coaches of other teams got extremely agitated when select players played against them and accused the coach and league of "stacking" rec teams with select players.