The former England and West Brom striker, part of the generation of black players that first made the breakthrough into the English game, is the uncle of Reading striker Jason Roberts, who refused to wear the T-shirts at the weekend along with Rio and Anton Ferdinand.
He believes that unhappiness with the four-match ban given to Terry for racially abusing Anton Ferdinand is behind the protest.
"There is a feeling that John Terry has been let off lightly," said Regis, quoted in the Guardian.
"You are not going to stamp out racism with laws - it is intrinsic to some people. But where it rears its ugly head the authorities have to stamp down and, if they don't do it with the right force, it gives the impression that it's okay.
"Black players have been voicing their opinion for a long time but feel it hasn't been listened to. They were unhappy at the time it took for the FA to sort things out - a whole year in the John Terry case.
"Then Luis Suarez got eight games, while Terry got four - what is the difference? The panel's assessment was that Suarez said the word several times while John Terry only said it once?
"Come on. Do we have zero tolerance or not?
"This is a different generation from mine. We had to put up with abuse. They are more articulate, they have more confidence and they want a clear and vehement message given."
Meanwhile, a national anti-racism organisation has called for a summit meeting to tackle the grievances of those players who boycotted the T-shirts. Show Racism the Red Card says it understands why the players refused to wear the shirts.
A statement from Show Racism the Red Card said:
"We fully understand the anger of the Ferdinand family and Jason Roberts in relation to the FA handling of the John Terry case. Both Rio and Jason are long-standing patrons of our campaign and are recognised in our Hall of Fame for their work.
"The issue of not wearing the Kick It Out (KIO) shirts at the weekend highlights the displeasure of certain players in relation to the footballing authorities' handling of the incidents of racism in the game.
"We call on the players involved to now sit down with us, KIO and the PFA to draw up a plan of action to present to the footballing authorities and Government."