If you rig it properly it will provide plenty of grip.
A tree trunk protector would just slide down the tree unless you looped it back through one of its eyes and connected the winch to the remaining eye. But this is not safe use of a tree truck protector.
I use a tree trunk protector 99% of the time. Sometimes it is not practical or I just can't be stuffed getting it out for a light winch. But then again I will also get out the chainsaw and cut down a tree or use the bull bar to knock it over if I consider it necessary.
As for only using for being stuck in the snow, I fully expect that someday before long he'll be stuck in something other than snow and say, "Hey, I've got a great 8k lb winch" and end up, at best, breaking something. It takes a lot of experience to know when stop and say, "No, my tools aren't capable of that." And he said the winch is for show. Based on that, and other comments, I'm guessing he would be reluctant to say, in a real stuck situation, that his winch/mount can't handle it. That wouldn't put on a very good show.
I am yet to see a winch fail in such a way that there is any significant risk. The risk is simply you don't get out of where ever you are stuck. The mounting is a different issue, but from the pictures I can't really tell whether it is safe or not.
In regard to knowing whether something is not capable of the job, sometimes you have to use what you've got and hope it works.
But I am not starting another debate with you as it goes nowhere.
Currently he has a winch that suits what he intends using it for and he is happy with it. I have also purchased a cheaper winch in the past (Warn Magnum) and know the false economy of buying cheap stuff as you end up throwing it in the bin. But I know a number of people who have cheap winches and are very happy as they are not serious off-roaders and may use the winch for the occasional light recovery.
I think he has learnt that he has to be careful about what he brags about on this forum. He also now knows what a air portal is, and I don't think his disco will be climbing anymore trees. He has taken on board all the criticism and appears to want to learn. We all had to learn somewhere, even though some refuse to.