The fly-half’s controversial omission continues to dominate the build-up to Scotland’s four-match Autumn international campaign, starting against Australia at Murrayfield on Saturday.
Thomas, no shrinking violet himself on or off the field, believes boss Gregor Townsend was right to freeze the 30-year-old out of his squad.
“He’s probably Scotland’s greatest-ever individual player,” said Thomas. “But no individual is bigger than the team.
“If an individual doesn’t contribute to the team, that could end up being your downfall. When you have a great player like Finn, a maverick, there’s also the prospect of an individual failure.
“When he tries things that come off, everybody cheers it. But when they don’t come off, who's cleaning up after him all the time?”
Thomas, in Glasgow this week as the face of the Tackle HIV awareness campaign, also leapt to the defence of Russell’s replacements, with Blair Kinghorn, Adam Hastings and Ross Thompson set to compete for the ten jersey this autumn.
“We need to realise these aren’t rubbish players,” he said. “They’re not bad, they’re not being picked just because he didn’t want to take the risk of Finn.
“They have different attributes, different leadership qualities that he sees as more relevant to where Scotland are as a team now.”
Russell shone in the club colours of Racing 92 as they beat Montpellier, a statement performance that saw him named in the Top 14 Team of the Week. In the aftermath Russell expressed the view that international omission could help him in the long run, a reaction that Thomas was buoyed by.
He said: “The sign of any good player is longevity in their career. No player goes through a long career without being dropped, having injuries or setbacks and having to adapt.
“It’s a sign of maturity from Finn, it’s a sign of how much he wants to get back in. He’s not rebelling against it, he’s not saying he’s better than it or Scotland aren’t good enough for him.
“It shows where he’s at. He’s not sulking and he wants to come back as a better individual and a better team player.”
Tackle HIV, a campaign led by Gareth Thomas in partnership with ViiV Healthcare and the Terrence Higgins Trust, aims to tackle the stigma and misunderstanding around HIV. Visit www.tacklehiv.org and follow @tacklehiv