This is a shitshow for everyone involved.
Tom & other carvers who "chase thinness" when it comes to stems because they "disappear" in your mouth, are uber comfortable, & etc., don't want to give up doing it because for many smokers it's a plus. A sales feature.
But if the high spots on someone's teeth happen to align just so, with a pressure point landing on a thin spot, such stems will crack in a heartbeat.
The lesson, obviously, is clenchers shouldn't buy such pipes in the first place. They should be considered in-hand pipes. "Holders"
But how can they know unless the seller can determine stem delicacy and tells them before purchase?
The best retailers will be glad to do so---if buying from Smokingpipes, ask to speak to Adam Davidson. If Blue Room Briars, either Jesse or Scott will be glad to answer any questions along that line, and are qualified to answer. I'm sure there are others.
But buy from a photo, while in a different country, with plastic, and no humans involved?
Welcome to the Internet Era.
Back when pipes were sold over the counter at B&M's, such subtleties were part of the in-hand examination.
I can think of no solution to this case where everyone will be happy. The seller thinks anyone who wants a small artisan pipe knows what they were getting into stem-wise, or, if they didn't, they should.
The buyer is rightfully upset that he spent a good chuck on a marquee name pipe and it broke within 48 hours. And the only way out of the woods is to spend more money.
All I can suggest is if does get sent back to Tom (or one of his people) to be re-stemmed, that the new one be made FOR a known clencher. Keep the funnel fairly narrow, and the thickness behind the button between .165" and .170" (It's no more work... it would be slightly less, in fact.)