He has always loved Nvidia. I recall posting pics in the "other" thread were he would use Nvidia ad placement but only use AMD CPUs but would refused to put up Radeon product placement. It's stuff like that. He even defended Nvidia when Kyle Bennet (defunct HOC) broke the news that Nvidia was trying to steal branding from Radeon, using GPP.
Dunno if you've realised yet but Steve currently has zero, nada, nothing Radeon wise on display intentionally to work people like you up - it isn't by accident or related to any bias whether real or imagined. They are actually doing it intentionally right now to try and manufacture drama - though no one aside from some individual forum posters seem to be biting.
He used to have both nVidia and AMD Radeon product placement prominent for years regardless of any bias (you can go back through his older videos) then one day they arranged stuff differently, all hell breaks loose.
Now they are intentionally making sure to put nVidia stuff first and foremost and hide anything Radeon for the LOLs.