So, signal is all about privacy, but when they chose a cryptocurrency, they didn't chose based on privacy. If privacy was the point, why not choose Monero, a mainstream coin which already has a reputation for privacy? So, if privacy wasn't their main concern in choosing a cryptocurrency, it's perfectly reasonable to wonder what
was their main concern. And given that MOB's only unique characteristic (as far as I can tell) is the deep pockets of their foundation (because they allegedly own ~85% of MOB tokens, worth Billions), it's not much of a stretch to assume that those deep pockets are the reason that MOB was selected.
For a crass comparison, let's say you've got a friend named Bob. Bob likes blondes. He loves 'em. He's always talking about how he loves the blondes and could never be with a brunette or a redhead. One day you bump into Bob, and he tells you that he has just married a bald chick, who just happens to be very wealthy. How strange, that this guy, who always harped on this one feature, suddenly made a decision that was not based on that feature at all! Clearly, some other feature was the driver of his decision. Now, that doesn't necessarily mean that Bob is a gold digger. But wouldn't you wonder?