It's has not been a question of which is safer anymore, MacOS notwithstanding, but of which you trust. It's either an OS that can be exploited by the vendor, or a 3-letter agency, by design, or trusting that someone will audit your open source software and look for exploits, unless you have the time and expertise to do it yourself.
Moreover, Linux users have never felt safe by the lower market share, but by how hard it is to have anything running on a Linux system. It's has never been about not having 14,000 viruses to infect your computer, but about having to make it executable it to have it run.
Now, if I felt threatened by this new exploit, I could make my computer super safe by uninstalling the piece of software it affects.
These days, the main reason for people to switch to Linux, and not to switch back to Windows, is concerns about privacy and productivity. You said that, had the exploit been found on Windows, there would be an update; now remember that Windows updates shut down the system, while Linux ones are performed while the system is running and the user is working: a reboot is not usually necessary, and when it is, it doesn't take longer than usual to turn on the computer.