That's actually hilarious. Once you analyse it, it boils down to three things:

1. Ad hominem towards the devs. It's so idiotic that I won't waste my time with it.
2. Conflation of the flagship instance (lemmy.ml) with the platform as a whole. As if you had to use lemmy.ml to use the platform (you don't).
3. Incorrectly assigning privacy concerns of social media as a whole to Lemmy in specific.

The third point actually deserves some clarification: no matter if it's Twitter, Reddit, Facebook, Mastodon, Lemmy or any other sort of social media, you should be extra careful with what you share, as it might eventually bite you back. It is public communication, treat it as such; it is not private conversation. Regardless of Lemmy storing it or not, consider what you share publicly with the internet as potentially staying forever, and be mindful with it.

So all three points are actually invalid. This might convince some irrationals to stay clear off the platform, but frankly? This is actually good for people here.