You could make a reasonable case for theft of services rather than rape if a client engaged the services of a prostitute, and then left without paying (the sex then being consensual, but the contracted payment being withheld).

Reading the Inquirer article, it suggests that the prostitute in question agreed to sex with two men for $250, man 2 turns up with a gun, and she was then raped at gunpoint by 4 men. There appears to be no suggestion that the gun wasn’t produced until after the sex occurred. That being the case, I can’t see how you could ever possibly hope to be able to prove “armed robbery” but not rape.

Either the apparent facts of the case are proved to be true, in which case all 4 men are guilty of rape, or there isn’t enough evidence to prove those facts, in which case there isn’t any evidence for the “armed robbery” either.

So I’ll provisionally chalk that one up to “stupid judge who should be looking for a new career”.