@MattAU I agree with you on your point about the clear difference you are making on the advocate vs evangelist word choice. I also understand it sounds like you motivation is tied to the support aspect of the community more so than the brand and their recent decisions.
I find myself in a similar situation with the brand of coffee that I drink. There is a local coffee shop that I have been going to more often, that have similar values to the brand that I like to drink as a treat once in a while over the home brewed coffee pot. Even if the original brand is creating red cups or littering on Mars (fake news?) I still like to drink the coffee. But now I am drinking coffee in both places.
In attempt to relate, I got on a tangent about coffee, I think it is great the time you put into helping Thunderbird users. I did not realize the part about being a law office either, that sounds like you get into a diverse kind of conversations.
Indeed, I can get behind the supporting users as a hobby that does not have to married to a company ideal, but maybe we can get behind a common goal to satisfying users while helping them find a support solution? Mozilla’s support’s commonality here might be supporting users of open source products like Firefox and Thunderbird.
It is definitely not an all or nothing list or rubric of what a high value contributions, the community is made up of a spectrum of skills, talents and motivations in my mind.