Question about House episode "Last Resort" [SPOILERS]

[Zakama]

I watched "Last Resort" last night, and still can't figure out why House gave the gun back to the guy. Can someone who understands explain? :smallconfused:

[kpenguin]

House's obsession the diagnose and know things in general. House didn't know what the guy had and he could only find out if he gave him back the gun.