That seems substantially better than the usual approach (of either an acquihire leading to an immediate shutdown or an acquisition leading to an inevitable "our incredible journey" shutdown later).
There are 220 people from all over the world who have contributed 20 or more commits to Zulip, and thousands more who've contributed code, volunteer translations, ideas, thoughtful questions, and in so many other ways.
Personally, I find remarks like this to be extremely disrespectful to all of those wonderful people and their open-source work.
This idea that devs owe their continued free service to an open source project they released in the past is a crazy one.