"Doing so would make apps like Signal, Telegram and WhatsApp entirely insecure" is what makes running security-minded programs on non-free, user-subjugating, always-untrustworthy, proprietary OSes a joke. People get a sense that they're safer from malware then they really are and they think they get to keep their proprietary conveniences as well. Openwashing will not help you.
I know it's a lot of work to learn new things and change your views and your behavior. I understand that software freedom is differently political than what you're encouraged to adopt, and software freedom requires you to consider more than what's listed in virtually every features & money-based ad campaign from monied proprietors. And I get that coming to terms with the consequences of software freedom runs directly contrary to believing that you don't need to think any further than what proprietors and their "open source" friends tell you to think about (because no proprietor frames their offerings in terms of the freedoms to run, inspect, share, and modify the software, hence proprietors are more likely to sanction the open source movement which eschews these values and even celebrates partnering with proprietors like Red Hat's recent uncritical commentary on Microsoft's software and Microsoft's new campaign regarding "Linux"—no mention of GNU which might bring software freedom to mind). But in the real world you need to stop trusting proprietary systems to keep you safe, respect your privacy, or other practical consequences of software freedom. Proprietary software wasn't designed to do that and therefore that software never will do that job. There is no middle ground which allows you to run proprietary software while retaining the benefits of software freedom. It's time to value software freedom for its own sake.
Even if all published software were free, exploits like these are possible because all complex software has bugs. Perfect security is not the issue. The issue is who gets to control their own computer and how we treat each other. Even after these exploits are published by WikiLeaks and people have had time to consider them and protect against their adverse effects, proprietors will still have power over users who run their proprietary software. Users won't be able to tell what other exploits are out there and therefore it will be harder to protect against them. The difference between proprietary subjugation and software freedom becomes more clear: Free software users will be able to run, inspect, improve, and share improvements with others making that software more able to prevent future attacks. But proprietary software users won't be allowed to do the due diligence they need in order to help themselves no matter how technically skilled they are or how willing to repair things they are. No computer user deserves to be treated that way. It will take a lot of work to get people to understand why they too should care about software freedom even if they're non-technical (like most computer users are). So I urge you to understand software freedom for its own sake and to try to help others understand as well.
Relatedly, the Free Software Foundation's "Respects Your Freedom" campaign has some new hardware on the list. I recommend buying some and using it, even if it's not up-to-date with the latest capabilities and seemingly expensive for what's offered. We need more people to invest in free replacements for proprietary, locked-down, user-subjugating systems. We need to make investments in our own collective future by funding the free products available today so we can have modern, highly-capable, and fully user-controllable POWER8, RISC, etc. systems which will respect the owner's control.