imi

The labels "vegetarian" and "vegan" usually refer to a persons diet.
Some vegetarians and possibly more vegans extend their choice to include other animal products (leather, wool, bone etc...). The labels are in no way strict. It all comes down to an individuals choice and the way they describe themselves.

Back to OP's question, some vegetarians and vegans are good with riding leather saddles, some not, some if the saddle is second hand...

It's even possible to be a "living-off-the-land" omnivore, who only eats meat and fish caught or raised and killed by themselves - or milk, wool, honey etc from their own animals - who would not buy a Brooks saddle... but may try to make one themselves from a cow they slaughtered with their own hands!..

I'm all for making fun of everyone who isn't even remotely different!

(meant as good natured joke y'all!)