The hobby repair shop can only be liable for a very small number of bikes, those they worked on. You cannot restrict the number of users of free source software, and you cannot restrict the user's risk profile. Like "good enough for an offline arcade game, but nothing else". Analogies have their limits.

But yes, lawmakers will decide, and given that they for instance try to de facto prohibit aftermarket OpenWRT installs, I have a guess how they would decide.