Intelligence of Infection

[nireth]

The way I see it is that the virus didn't control his actions, but alter his perception. Let's assume he was at the very least familiar with the Catholic suicide = bad concept (or even the plain human suicide = not exactly the most awesome thing concept): in that case the virus could've amplified and emphasised this idea in his mind to a point where it was impossible for Red to go through with any attempt (e.g. put noose around neck + kick away chair = suicide = AGAINSTTHERULESAWFULOMG!).

But then the furnace was something of a backdoor, something he could bring himself to do, because locking himself in the furnace was not something immediately and obviously resulting in his death. Say without Philip over time the virus conditioning would've reminded him that being locked in furnace = starving/dehydration = suicide = AGAINSTTHERULESDAMMIT! and made him uneasy to a point where he'd have to get out eventually, but as it was I believe the notion of I AM COMMITING SUICIDE in his actions was not strong enough to trigger the I AM ACTING AGAINST THE RULES response.