I mean, if it was me...and this is just because I'd be thinking about all the awful people or situations he/she could end up in...I'd probably do it, get the pig checked out and after quarantine and depending on genders of existing and new pig, see if they would bond. If not, I feel like I have enough resources to find it a good home. I guess some of it too just depends upon your funds and if it was opposite gender from your herd whether you could spay/neuter first.
I get that sometimes situations change and people need to re-home, but the fact they outright say in the ad they have no interest in the animal....why get it in the first place?
I'm totally not trying to convince you to go swoop in and save this little pig though. Lol. I'll be interested to hear more once you set up a meeting.