their first pre-release was in 2013: https://github.com/mailvelope/mailvelope/release/tag/v0.7.0b...

It's been posted on HN before: https://news.ycombinator.com/item?id=8257148 (this link is from 6 years ago)

My guess it's a response to this HN discussion from earlier today: https://news.ycombinator.com/item?id=22888488

I had the same doubt. It's been listed on PRISM-break for long.