Is the mortise face funneled ? If not, I would think a tenon like that would be a way to make it easier to insert without removing any extra briar from mortise / shank making it weaker. Especially on a small piece of briar to begin with.
Restoring a Surprising Silver Treasure: a Robinson 8494 Quarter Bent Paneled Tomato - https://rebornpipes.com/2019/03/12/restoring-a-surprising-silver-treasure-a-robinson-8494-quarter-bent-paneled-tomato/
A england singapore connection is discussed in the above post.
I did not like them in the beginning, but then again I dont think I could have picked out what flavor i was tasting that I didnt like. I like them now. Its kind of like the bitter/sweet thing with beer, I think burley has that, which may be acquired for some.