I have two answers.
The snarky answer is that when one writes a paper one has to make simple things sound as complicated as possible in order to make the paper look like you've discovered something interesting.
More likely it really does have to be this complicated considering that handling security when combining content from multiple sources cannot be made simple unless you make it trivial (no trust or complete trust).
Can you really claim an exception for FOSS?
Given that FOSS always gets you #1, it should be concluded that you can only get #1 and #2 or #1 and #3.
You fail to realize that ultimately both versions of Firefox must eventually go through the same layers of Linux in order to do pretty much the same thing. The story is that the Windows version is still faster even though it has a whole extra layer to go through.
It is not even a comparison of Linux/Windows but of Linux and Linux+Wine.
The Linux build of Firefox is the problem here and has nothing to do with the trade-offs between how Windows does things and how Linux does things.
Besides, how can you say that everybody should fall on one side of the Performance/Reliability trade-off? Such things are case-by-case by definition.
"Who alone has reason to *lie himself out* of actuality? He who *suffers* from it." -- Friedrich Nietzsche