I'm not saying you shouldn't doubt them, I'm not sure where you got that from. The point is that this is not just "some random person" fork's, it's by someone who has established himself in the industry, so like it or not there IS a reputation behind this brand and piece of (open source) software. If the browser is good or not that's another discussion (which I'm happy to have), but the comment I was answering simply dismissed the idea of using the fork because it's by some random person, and so I pointed out that's not really fair.

What about if someone made a good X, then tried to make another good X? Is that still a midlife crisis

It's called "appeal to authority", and it's a fallacy only in case where the authority is not relevant to the area in question. So, if a Nobel prize winner in literature gives advice on economics or quantum physicists or medicine, then their credentials are irrelevant, and appeal to their authority is a fallacy. If, however, a prominent physicist talks about physics, then it doesn't mean they are necessarily right, but at least the likelihood of them being right is much higher than for a random person from the street. As such, having created successful technical products in the past suggests that it's likely next product may be worth something too. It's not a guarantee, but it's a relevant data point.

> haven't done much in a long time

All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?

> a reverse ad hominem

I think we call this an argument from Ethos. i.e. it leans on what someone is, rather than their persuasiveness (pathos) or how well their argumentation is structured (logos). It is not a particularly strong way to make a case, but it is a way to make a case. If you have a problem with it, you are free to speak of what you feel should be considered instead. I personally think "it's a cryptocurrency and therefore a scam" argumentation is lazy and not very compelling, but perhaps your target audience does not.