I had the same problem and simply sanded the tenon down to size.
It is somewhat surprising that the interweb pipe pages don't warn against cleaning acrylic stems with alcohol. I use only dish detergent and hot water on my acrylic stems.
The same interweb pipe pages also don't warn against keeping rubber stems in the light. My earliest pipes with vulcanite stems would look a lot better today if I had known that 20 years ago.
I learned about the acrylic/alcohol issue on another forum from a member who is either a chemist or materials engineer (can't remember which). The problem is that the information goes out and then disappears as threads recede in time.
Add to that that many people in the population have limited knowledge beyond pipe brands and tobaccos. A fancy new pipe is a lot sexier than information on how to maintain it.
People love to display their collections. They're less interested in hearing anything that might diminish or complicate that pleasure. They'll screen out information that they don't want to hear.
When the first batch of C&D Carolina Red Flake was discovered to be severely contaminated with mold, C&D asked for buyers to ship their tins back to C&D for a full refund. It was a full recall of the release. A lot of smokers didn't want to hear that, didn't want to believe what they were told about the toxicity of tobacco molds, and because it wasn't what they wanted to hear, they kept the tins to smoke. Also, some kept the tins because they thought that it would be rare and therefore more valuable on the secondary market.
Many pipe smokers aren't interested in caring for their pipes beyond minimal basic care. The pipes are tools for getting a nicotine buzz, not collectibles, not object d'art. When they've worn, into the trash they go.