Besides, it looks like the amount of cash that Mozilla got for stuff like Pocket or Mr Robot is tiny compared to their other sources of revenue. It doesn't seem something worth to taint their brandname and ethos for.
If you rule out Firefox, there's hardly any viable option for a modern, feature-complete and freedom-respecting browser. Chromium is OK, but those suspicious blobs don't look very appealing.
For me the most shocking part is that the FSF has a Firefox ESR fork, IceCat, which is hardly maintained and goes 2 versions behind mainline. They don't even bother patching CVEs...
Apple's problem is simpler as they own the code, and bugs are likely to come from understaffed engineering.