Whilst I agree there was nothing wrong with what anyone said... I have been thinking about this and do think it is a shame that we weren't able to find a more constructive way to handle this couple and their pig.
From their point of view it must've looked a bit like this:
Oh, our pet pig is cold, where can we get some advice? This Accidental Smallholder forum looks like it's full of knowledgeable friendly people, let's ask them.
Whereupon they are inundated with posts telling them their pig is an unhealthy runt and should be cooked, and they are cruel and shouldn't be keeping the pig. (Remember I'm telling this as I think it would have looked from their point of view - humans are really quite sensitive to criticism, I find. One critical post will weigh more than two or three constructive ones.)
I'm not surprised they left. Whilst perhaps we don't want to find ourselves in a community of pet micro pig owners, I do think we're more likely to educate more and change more minds with constructive inclusiveness than overt criticism. I thought Mandy's post hit exactly the right note.