What's the issue with Linux's architecture? Hybrid kernels aren't shown to be any more secure than a monokernel to my knowledge. There is something to be said that we don't make kernels for device drivers, which are basically their own operating systems, but that's common to all kernels.
Any of these are wrong.
Propriety systems are closed and obfuscate their flaws.
Also, (3) should raise some eyebrows for readers paying attention. Cool, Microsoft removed font parsing from the kernel, how wise of them. Wait a second, why was font parsing in the kernel to begin with? With win32k.sys, it shouldn't be surprising that Microsoft has to do more legwork to bring the attack surface back down to the level of other OSes. They're also exploring the use of eBPF in the Windows kernel too[2].
[1]: https://github.com/hfiref0x/UACME [2]: https://github.com/Microsoft/ebpf-for-windows
I don't see how the Linux developers' higher speed of fixing security bugs would in any way substantiate the author's claim that Linux is not "less secure than proprietary systems". He completely leaves aside
- the number of security bugs per unit time,
- the severity of the bugs in question, and
- the overall system architecture and the potential impact of security bugs in general. Needless to say, this is where the situation on Linux looks pretty grim compared to current "proprietary systems" (which has nothing to do with the fact that they're proprietary).