It also alleges some kinds of deep-state connections due to an early grant it received, but fails to present evidence of anything nefarious. Remember, Tor was a US government project too - it doesn't mean they control it.
It's clear the author doesn't like the woman's political views and affiliations with center-left causes, but unless he's worried about Signal selling tote bags during pledge drives I just can't see the relevance.
Also, Signal's client is open-source. You can verify its security claims. It's been independently audited. I think the builds are deterministic, or at least verifiable. The server is closed-source, but the client does not trust the server. And even contact discovery etc. uses SGX enclaves and other mechanisms to keep metadata from being visible. It's what makes the accusation so risible - Signal's security and privacy are verifiably state of the art.