Malthouse's 16th-placed Blues host fourth-placed Collingwood at the MCG on Friday night as Thomas takes on his old side for the first time.
Collingwood fans will probably give their 2010 premiership star a hostile reception, according to Malthouse, who coached the club from 2000 to 2011.
"Do you think that's going to worry me or him or anyone else? No," Malthouse said.
Malthouse claimed Thomas didn't get caught up in the hype about the Collingwood game, then admitted it had been a different sort of week for the 2011 All Australian.
"Only because you blokes want to make it a different week," Malthouse said.
"Don't take yourself out of this. You're the blokes who have been stalking the gate.
"He wants normality. He knows it's not going to be normality.
"But he wants to play football."
Malthouse said of course the fans were interested in the issue, and that's why they will pack out the stands at the MCG.
"The sideshow will be Dale Thomas. Absolute sideshow," Malthouse said.
"They go to watch Collingwood and Carlton play each other.
"You guys want to make it an issue and that's your job. No one could deny your role.
"But don't try to make it that it's our number one fundamental issue because it's far from that.
"It's hardly a blip on the radar.
"For Dale, it will be important to play the game for Carlton and not get tied up in the Collingwood stuff.
"You can make what you like out of it. Build it up.
"Make it the main focus. But how Dale goes, or how he doesn't go, won't have any bearing on the W or the L."
Thomas told Nova FM he wasn't buying into the media hype.
"I'm more than happy to let them try and build it up to something that it isn't," he said.
Collingwood coach Nathan Buckley says it's a marquee game for Thomas.
"He's taken the opportunity to move on to a new club and that test happens for any player who moves clubs," Buckley said.
