if you publish a game and I buy it for few dollars
do you give me the whole source of the game too ?
I'm not sure why you think sources of ANE have less value than anything else
you see, if someone build some apps, libs, whatever
and sell it as closed source with a licence price tag
in general he/she keep track of the time spent writing code, publishing, maintaining, doing support etc.
let's say a trivial ANE, that's probably a good week of work (if not more)
even if you price your time conservatively $40/h
those 5 days, at 8h per day, that's 40 hours of work, that's easily $1600 bare minimum
so what make you think the ANE producer should give away all that for free?