If, say, Signal was completely controlled by the CIA[1] and was thus evil, then having incoherent cryptography as described in the article would be a feature, not a bug. Being able to reject law enforcement requests would produce a false sense of security for the people the CIA was interested in surveilling. Responding effectively to law enforcement requests would reduce the value to the CIA of the ability to secretly backdoor Signal.

This effect was seen in the Apple vs FBI incident described in the article. The public perception of Apple as a brave defender of user privacy was greatly increased due to that dispute. For all we know, the FBI was in on the conspiracy. In return they might receive the fruits of such surveillance with the only limitation that they would have to disguise the source with parallel construction[2].

[1] https://en.wikipedia.org/wiki/Crypto_AG

[2] https://en.wikipedia.org/wiki/Parallel_construction