A number of points to make, first, the publicised incident was clearly intended as an act that transgresses social bounds and limits. The idea is that the actor is stepping outside of normal codes. So, those doing it conceived of it as "wrong", as far as society was concerned. They wanted something that would seem "sick".
Secondly, "wrong" doesn't necessarily mean "evil". It can mean not proper or usual. In this case, those who came up with the idea would agree: that's what was intended.
Thirdly, as outlined on the piggate thread, I think it is an activity that most of us would be disappointed to discover our university age children were involved in. And were a small child to approach a pig's head (or any item of food, not just charcuterie) willie out, we'd all make some level of disapproval known to the child.
So, it's something conceived as outside of normal bounds, it's something society would agree is not becoming conduct, and it's something we'd express disapproval of were our children to partake. I am surprised to learn there is a significant minority who say they don't think "there's something wrong with it". I suspect they are defining "wrong" as exclusively about morality.
So, is it immoral? That isn't what was asked, but to the extent that wasting food is morally wrong, then yes it is. Putting your penis into any food is a waste of that food, if it means the food won't be eaten. If the food is going to be eaten, and those doing the eating aren't aware of the preceding activity and if they are not eating it out of free, informed choice, then that too would constitute immoral behaviour.