There's some missing nuance here. Naomi Wu documented this much better than my summary, but the short version is that you need an IME keyboard for Chinese text entry, and the only one that's any good (and so, has a huge install base) is an application created and owned by a corporation with strong ties to the Chinese government.
When there's a security rake-in-a-darkened-shed that a large fraction of your users will step on, with a demonstrable risk to their life and liberty, I think reasonable people can agree that we're standing on the "hey, maybe we should at least pop a dialog about this" side of the line.
It took Moxie well over a year to come to the same conclusion, and then in a really lazy way as documented by the commit upthread. I'm starting to see him as a particularly unreasonable person.
First, I speak Chinese, I understand what the IME thing is about. I agree that the "Incognito Keyboard" flag is a miscommunication, it should say "Politely tell my IME don't use my input to make smart suggestions", but IMO it is more of an OS issue instead of application issue. Android decided this should be called "IME Incognito Mode", but in reality it is not enforced and merely a hint to the IME. Maybe in addition to calling out Signal, we should also try to convince Google to change the name?
For "pop a dialog about this", I don't know, that's an interesting idea, but it is hard to draw the borderline if you pursue this route.
For example, do you know that Tencent QQ bundles a full-blown endpoint security solution trying to "protect their users" and warn them their computing environment is compromised? To the point it installs a kernel driver to do the detection. Most of my tech-savvy Chinese friends believe this is bad, not only because the possible privacy dilemma but simply because it is not an messaging app's duty to ensure the user have a safe computing environment. Surely Signal can pop up a dialog about the IME concern, but what's next? When somebody bring up an interesting cross app side-channel leak on Android, should Signal scan the installed package list, try to flag any "suspicious app"?
"But what's next" is a slippery slope argument that isn't interesting. This particular issue is unique, and it makes sense to warn about it, and there's no really good reason not to when doing so is so trivially accomplished.
Hemming and hawing whether a line warning about a vulnerability that compromises a secure messaging app for over a year for any reason, but especially because of a shitty, arguably sexist tone argument not behavior I want to see from people who make security tools.
When there's a security rake-in-a-darkened-shed that a large fraction of your users will step on, with a demonstrable risk to their life and liberty, I think reasonable people can agree that we're standing on the "hey, maybe we should at least pop a dialog about this" side of the line.
It took Moxie well over a year to come to the same conclusion, and then in a really lazy way as documented by the commit upthread. I'm starting to see him as a particularly unreasonable person.