The guy doesn't own Signal. Signal is funded and released by Signal Technology Foundation, non-profit; either directly or indirectly through it's subsidiary[1], Signal Messenger, LLC. (Both registered in Delaware.) That means there's much more likely a legally cognizable conflict of interest if Signal is being used as a vehicle for self-enrichment. And flouting rules against such self-dealing provides greater than normal reason to distrust the security of Signal.
But that's all predicated on the existence of self-dealing.
[1] The Wikipedia page, https://en.wikipedia.org/wiki/Signal_Foundation, claims Signal Messenger, LLC is a subsidiary. There's no source provided, AFAICT, nor can I find one, for that claim. But Android says Signal is published by "Signal Foundation", and Moxie seems to be the head of both, so for our purposes--trustworthiness--the distinction is mostly irrelevant.
But that's all predicated on the existence of self-dealing.
[1] The Wikipedia page, https://en.wikipedia.org/wiki/Signal_Foundation, claims Signal Messenger, LLC is a subsidiary. There's no source provided, AFAICT, nor can I find one, for that claim. But Android says Signal is published by "Signal Foundation", and Moxie seems to be the head of both, so for our purposes--trustworthiness--the distinction is mostly irrelevant.