I feel like if you want to call something "rhetorical underhandedness" you should at least pay attention to which fork of the argument you're criticizing.

The original complaint was that if they were doing it to be controversial, why not do the same thing to viewer apps for Reddit or Wikipedia? But those are necessarily distinguishable. If the standard was that a viewer merely could load external NSFW content rather than was likely to, you would have to do web browsers, mail clients, podcast managers, file transfer apps, video players that can open external links -- it'd be most of the repository. And that would be far less defensible, because you can point to specific controversial Bible verses, but how are you going to make the case that generic FTP clients and web browsers are NSFW with a straight face? But conversely, how would you argue that a Reddit viewer is NSFW but a web browser that can open Reddit isn't?

The fork where they need "a sincere belief that these apps contained content unsafe for minors" was the other fork, where they're doing it because of potential liability rather than to make a statement. But that fork was flawed to begin with, because they're not required to think that it actually is unsafe. They could also be concerned that someone else could claim that and then even if the people claiming that are jerks and even if the jerks could ultimately lose, they could prefer to be risk-averse when they don't have the resources to handle things like that.