What could cause the captain of such a well-received vessel abandon the helm and move ashore so soon after launch?

The answer, alas, is a familiar one: people.

“Recently, I had an unpleasant experience […] where I was accused of distributing malware. Although I explained that the issue wasn’t caused by the app, the conversation escalated into personal attacks and harsh words directed at me.”

For a space fundamentally built on collaboration and a more pro social approach to building things together, it's very frustrating how common anti-social, antagonistic behavior is in open source, free license spaces.

To me it feels like a real and significant hinderance to FOSS, and I really hope we can collectively develop more awareness about this issue so we can hopefully address it :/

That's a pretty shitty outcome. And the LoucheBear character doesn't seem to contribute anything of value, just ignorant abuse.

Sounds like he should have demanded that they pay the asshole rate for support

Was there no easy way for the developer to block a random asshole?

Since clamav itself shows no signs of vanishing, this frontend going away might add a bit to the friction some people experience in using it, but the software itself wasn't that noteworthy. The treatment of the developer, though, was just wrong.