This is really silly. Signal has discussed repeatedly what metadata they keep. It might be sane to ask questions about that, except that every competing messenger keeps the absolute worst case metadata, generally in plaintext, nicely bundled up in SQL tables. At best, you'd be making the claim that Signal might... secretly be as bad as everything else.

And, of course, the source code does nothing to do address this concern; they control their servers and can run any secret fork they want. It's a purity test and nothing more.