How tall are you? I'm 6'2", which is above average but probably not outside the median for Western men, and while the knee room on most flights is a bit tight, I attribute that to most of the flights I'm on using regional jets and it's rarely bad enough to cause serious discomfort.
Regarding KLM, while my experience with them is limited it was better than any other airline I've flown.
The solution is 100% effective for those who utilize it. Your rationale applies equally to a vaccine: It is less than 100% effective for the people who do not receive it. I would certainly question which empirical documentation you can point to that shows that abstinence from both unprotected sex and shared needles "simply doesn't work" in this context.
In short, you should have stopped with the point that the abstinence argument ignores human nature. But then again, if it were human nature to abstain from all risky behavior then we wouldn't be having this conversation and there would be no abstinence argument for the simple reason that there would be nothing to argue about.
Does abstinence work? Yes, with absolute effectiveness for those who choose it. Are all people capable of sticking to that choice even if they are rationally capable of making it? Of course not. But that does not mean abstinence doesn't work. It just means that people suck at behaving rationally, which is simply not news.
If you want to put yourself on the map, publish your own map.