Security is not everything there is to want from a messenger. Due to its centralized approach, Signal is having a problem with financing and I doubt it can be easily solved. It had a large downtime recently. Also, it becomes an easy target for all kinds of bad actors, since it's the single server. I trust it less for those reasons, even if it's "secure" by your standards. I just don't see it being secure long-term, not enough to suggest it to my friends or use myself.
People who truly need privacy in the short term, should consult a professional and not trust random comments from strangers.
People who truly need privacy in the short term, should consult a professional and not trust random comments from strangers.