squid830: That pig wants to die though. So you're actually doing it a favour. If it were rescued it would probably go insane attempting to philosophise with fellow pigs who won't be able to understand what its even saying.
That and since the pig is literally walking bacon, it would end up dead soon enough anyway.
geckosoup: Well...it must be the only pig in the history of the entire world that actually wants to die...And at no point does the game mention a super-intelligent pig, just a pig, which are, come to think of it, the 7th most intelligent animal on earth; they have the cognitive and problem-solving abilities of a 3 or 4-year old child, so way more intelligent than a dog. They also experience the same gamut of emotions we do, including fear, pain, torment, loss, grief and loneliness. They look forward to things. They anticipate things. With all this in mind might its intelligence (which we only witness after taking the potion that allows us to talk to it) be equal to that of any other pig it might meet? And as for it being walking bacon...I'd take it to Red Fighter and make a home for it (and other rescued pigs)...a bit like Esther the Wonderpig in Canada (look her up on Facebook and then tell me you feel comfortable eating a bacon sandwich :) ) Anyway...like I said before. Humour the vegan :) I haven't eaten meat since 1980...he'd be perfectly safe and happy with me :)
(Yeah yeah...I know..."it's just a game" :)
When you talked to him, did he not say he wanted to die? That's what I'm basing this on. So yeah, maybe it's the only pig ever that wanted to die - possibly also the only pig that actually understood concepts such as death in detail, similar to how a human would view it. Sure it mainly wanted an end to its current existence - which in theory could be achieved by "rescuing" him - but there's no guarantee he'd ever really be happy.
BTW you're probably aware you can easily spare the pig - it just means you need to use an alternate path to get at what you want (i.e. the information guy who plays cards in the casino). I've never tried this path, but I assume you don't miss out on too much content that way? Pretty sure you still get sent to the bunkers as per usual (and I can't recall if the "Death Tunnel" was before the pig or afterward - if afterward, maybe you'd miss out on that particular quest).
As for Red Fighter - that's always (potentially) possible - though I'm sure others would want to get at that juicy bacon, since you can't get anything else from a pig. Actually that's not entirely true - if society gets to the point that "murder" is something that you need to cover up, having a piggery is great for easily (and quickly) disposing of bodies - they eat pretty much anything, leaving practically no evidence.