Free markets only work if there is a downside to a bad investment. The gov't didn't do anyone any favors in the long run when they saved GM. As you point out, there were 2 other major car companies that'd have bought parts from those suppliers and it's highly doubtful that GM would have simply disappeared if the normal chain of events had continued.
Gov't involvement in markets is BAD. Allowing dirtbags like those in Washington to chose winners and losers is BAD.
Disincenting careful inspection of potential investments through gov't saving people from losses is BAD.
It is highly likely that this truck and the parts suppliers all would still be here had Obama not stepped in. The fact that "conservatives" defend his intervention speaks clearly to the sad state of so-called "conservatism" in this country.
