Also, don't forget that no matter what, you are unlikely to
be sued. Larry didn't write a waterproof, lawyer certified,
do-what-I-want-or-I'll-sue-you restrictive license, like RMS
did. Larry wrote a statement of intent. Basically, what Larry
said was "I made this piece of software. I'm nice, so I make
it freely available. I like you to be nice to". Not a "you have
to be as nice as I was".
Also note that when the AL speaks of making modifications
available, it nowhere states that those modifications shall
be under the AL.
You say that "freely available" is a bit unclear, and you
offer an interpretation. Now, the AL is unclear in many
respects, but not about its notion of "freely available".
It even defines the term:
"Freely Available" means that no fee is charged for the item
itself, though there may be fees involved in handling the item.
It also means that recipients of the item may redistribute it
under the same conditions they received it.