If vaping under a blanket on an airplane is selfish, offensive and/or harmful AND vapers believe this, then our opposition has won.
If I were to not vape on a plane it would primarily be because I didn't feel like it or because of (my version of) common courtesy. IMO, common courtesy on a plane would mean no one is sleeping where others are awake, no one is sucked into a movie / TV show that others are not able to view, no one is reading own reading material, simply because they can. None of these things offends me, but all are arguably selfish. Even the baby/child crying, the person snoring or the loud talker aren't to me offensive, though I can feel the annoyance factor they carry into a public situation, which often humors me.
Put yourself in ANTZ shoes for a minute or two. Now think of a place, anywhere on the planet, where vaping would be a good thing to do. Unless you are selling ANTZ short, the reasonable conclusion is that nowhere on the planet (or up in the air, mid-flight) is good. Zero exceptions. Each place that a vaping enthusiast considers a place to vape, needs to be shut down and made an example of "harm" or "offense" to others. This does include vaper's own home/property, if sold on harm aspect inherent to anti-vaping rhetoric.
Common courtesy, on a plane, would be to ask those immediately around you, who may see the vapor, if they are okay with it. Yet, if vaper is under a blanket, then help me through with understanding who may see it, smell it, experience the exhaled vapor? If lights are down in the cabin for public nap time, then chances are very good that no one will see it, smell it, nor experience exhaled vapor. To the degree it can be argued they might experience it, let us also be clear with that argument that people on a plane are all experiencing exhaled air of all other passengers.
So, common sense comes into play, from both the vapers and non-vapers. All of what is above in this post, is common sense spoken to the non-vaper that vapers ought to be well aware of by now, unless you just started vaping say 3 weeks ago. Common sense from vaper perspective would be to not cloud chase, nor blow vapors directly at people. Common sense would suggest that it is not desirable to fill the space of the airplane cabin with vapor. But common sense would also note that is is implausible for one vapor to do that, and improbable that a vaper under a blanket would be able to achieve that.
Anyway, I still reside firmly in the "vape everywhere, with respect" camp. A plane in mid-flight would be the type of place that would test that for me, but not something I'd rule out. I live in the U.S. and am well aware of public usage bans popping up all around me. Fortunately, for me and other vapers in my state, I live in a location that sought in 2013 to exempt eCigs from public usage bans, or more precisely wishing to note that clean air act for the state did not apply to exhaled vapor.
To say these laws are popping up based on existence of vapers is I would say around 5% accurate and reality is that 95% of the reason these particular set of laws get proposed and legislated is due to ANTZ and their approach to determining (for everyone) where are the good places to vape currently and what legislation can they get away with right now given the makeup of the local and state politicians.