Of course, it's completely horrid taste
I'm sure that was the point of the filmmakers and it was the point of virtually every successful exploitation filmmaker from Dave Friedman and Don Sonney to Kroger Babb to Hershell Gordon Lewis to Tinto Brass, etc. A movie like this would never pass Hollywood muster and so could instantly sell itself as being outside the mainstream.
Obviously, the movie is not meant for everyone, but an important point can be made that tickling isn't always done in a fun-and-games manner. And believe me, I LOVE tickling done as fun--that's what I'm all about.
However, it does no harm to remind people once in a while that tickling has been and is, unfortunately, sometimes done maliciously. Do I derive "pleasure" from the Holocaust II scene? No. But I understand the seriousness behind it. There's no pretense to hide that it is torture, unlike what you would see, for example, in some cartoon interrogation scenes with children being tickle tortured for information. Personally, that disturbs me more, because the seriousness of what is obviously torture is "softened" by using tickling in place of alternate forms of violence, which would strike viewers, I believe, much more viscerally.