I think you're likely misunderstanding the context of **why** a champion is disabled for LCS.
Let's start with a standard player first. He/she hops on at night to play a few games. Wins some. Loses some others. Maybe the bug even showed up in one of the games. But, at the end of the day, not really too big of a deal. At most people's level of play (Gold and down), a single bug will rarely cause a big shift in the game since individual and team play will make up for any of that. (And, to be fair, Riot definitely has disabled champs with gamebreaking bugs - Hemier and Yorick are the two most recent that come to memory.)
Now, let's look at LCS. You are talking about people's careers her (you laugh...but these guys bring in some serious $$$ from some estimates I saw). And, remember, every LCS game is a potential to move closer or farther away from going to championships. So, say two teams are battling it out and the Shen bug appears. It may not even be clear that that bug caused the game to be lost or won for the respective teams. But...**it could have been**. At this point, the team that lost now has a legitimate excuse with Riot that not preventing that bug from occurring ultimately cost them prize money, promotions, advertising dollars, whatever. It's a big deal when careers and money get involved.
I believe this is why Riot gives special care to disabling champs in LCS - particularly with those tricky, hard-to-find issues (like the Shen bug). A Riot employee would have to confirm.