It wouldn't be commercial suicide for a company with a huge, rabid following like Valve
Er, yes it would. Anyone who is of low enough IQ to be a rabid fanboy is equally dumb to change his allegiance depending on what he reads on Kotaku. Look at the PS3's lack of success vs the PS2, which had an equally rabid (and 100x larger) fanbase.
You are also conveniently overlooking the fact that even if Valve doesn't cutoff everyone from a game doesn't mean that it won't cutoff YOU
Yes, that happens, and when it does it's unfortunate. It's a problem with Steam which shouldn't happen. But I bet it happens to Microsoft's Windows activation thing, and to McAffee's register of who owns their software, and to WoW on occasions. Databases screw up sometimes. There's no excuse for not getting mOOzilla et al back on track ASAP, but it's hardly unique to Valve, and it's hardly common.