Last week, Paul Kenny was granted bail and banned from attending games after admitting racially abusing Sinclair.
"It was disappointing," said Gers goalkeeper Foderingham, an ambassador for equality group Kick It Out.
"No-one wants to see that in football, especially at a club I represent."
Commenting on the incident, the 26-year-old Englishman said it was "difficult when one idiot comes and starts to behave like that".
"The club has dealt with it accordingly," he said.
"The Rangers fans have been fantastic. All season and since I joined the club, they have been superb.
"I haven't (spoken to Sinclair), I can understand that he is probably upset and frustrated, but hopefully he will be all right."
Meanwhile, Foderingham admitted the Rangers players are still getting used to new manager Pedro Caixinha's methods since he took over from Mark Warburton.
"It is a different style of play," he said. "He is an intensive, aggressive type of manager who wants his sides to play as such and it will take time for the boys to adjust.
"We are doing that at the moment and hopefully we can get a good pre-season under our belts and have a good go at it next season.
"Until we start winning football matches on a regular basis, the question marks are not going to go away.
"So what we need to do is work together as a squad, as a management, as a club and get back to winning football matches."
Wes Foderingham acknowledged the hurt "one idiot" caused Scott Sinclair but says the fan, who admitted making racial gestures at the Celtic player, did not represent the Rangers support.