...At which point, you're trying to convince me that this group of rioters had the political savvy to hide their real intentions behind the accusations of cheating...
No. I don't think that a bunch of people stormed the Capitol building because they are racists, trying to pretend otherwise with the veneer of protesting a stolen election.
I think that part of the movement that so enthusiastically fell in behind Trump are a bunch of conservatives who are fearful of the future and distrustful of their elites, so have developed a strong anti-establishment streak. But there's a series of intertwining beliefs and attitudes that make these people up and got them to that point. One of those is, I think, basically racism. This is not the same as saying each individual is racist, or that racism is the primary motivation of anyone when they do stuff. But it is part of what feeds the wider movement.
At an extreme level it's outright white nationalism, but even at a moderate level it's a fundamental view of America as a majority white, Christian (Protestant), gun-ownning, capitalist country. All these foreigners come in, ill-educated, with other religions, culture, political views, etc. and bit by bit erode the soul of their country. Even the black population are not really quite American, not in the sense they understand: a poverty-stricken, drug-dealing, criminally-inclined underclass with an all but foreign "urban" culture and a distressing tendency to vote left-wing. Non-white people have grown in population share, occupied more positions of social, economic and political power, frequently espouse liberal-left views, and it feels to some whites - especially those inclined to conservatism - like the white-dominated America they grew up in and were comfortable with isn't really there anymore. It's a potent image when some heavily black population cities, late in the election count, overturn Trump's lead: oh, the symbolism. And that it's so much easier for those who believe black people are inferior to believe they would cheat. These non-whites, from their "shithole country" stock: corrupt, lazy, who even after white men created and gifted to them technology and civilisation, they'll still screw it up.
This strand of thinking really exists, and it has a lot of its expression amongst the Trump core. That's why 2016 he could go in with a flagrantly iffy history on race and openly rage against foreigners, and far from hurting him, it helped propel him. This strand is a view that ties in very naturally with a wider feeling of insecurity and national decline - loss of manufacturing, wage stagnation, inglorious, victory-free, military slog, the rise of China to challenge the USA, the general discomfort of change and unfamiliarity of the new, etc. All of these coalesce together to a Make America Great Again movement. Let's really not pretend race doesn't exist as part of it.