The exact same thing has been said about CBT/GET, which is supposed to be effective and safe too. I have spent enough time and energy evaluating the evidence for CBT/GET to know this is questionable, and I have bad life experiences with GET. I have little reason to doubt whatever limited evidence there is for Rituximab so far, but my concern is not just about "severe reactions" but ANY significant decline in health whatsoever which would make life not worth living anymore.
Years ago I had intravenous EDTA chelation therapy, which now I know was quackery but is still supposed to be relatively benign. I have made many cumulative mistakes, but that treatment happened to coincide with the beginning of a rather dark phase for my health, and maybe this is irrational enough to require CBT (hehe), but considering that I cannot even tolerate a daily aspirin anymore without a decline in health, the thought of infusing something like Rituximab scares me.
Doesn't seem irrational to me.