As I said on #debian-devel, I think the real problem here isn't the wording of the license (though changing the "musts" to "mays" certainly papers over the issue, and makes the license free again), it's that the entirety of section 2 is attempting to solve technical issues legally. This just plain isn't what distribution licenses are for.
IMO, section 2 should just be removed, and taken to a standards document which could, in turn, be fleshed out to be even more technical defining exactly how and when font name versioning should be done, etc. This is a problem not unlike library ABI versioning, and it definitely needs people steering a committee of folks to draw up proper standards, but those standards can not be enforced both legally and capital F freely.
To put this in perspective, if I distributed some shell scripts under a license that said "you may freely modify and distribute these scripts, provided your versions maintain POSIX compliance", that would be daft. New versions of the script no longer being POSIX compliant would certainly make them violate a standard, and would make them buggy in many people's minds, but it shouldn't make them illegal.
As I said on #debian-devel, I think the real problem here isn't the wording of the license (though changing the "musts" to "mays" certainly papers over the issue, and makes the license free again), it's that the entirety of section 2 is attempting to solve technical issues legally. This just plain isn't what distribution licenses are for.
IMO, section 2 should just be removed, and taken to a standards document which could, in turn, be fleshed out to be even more technical defining exactly how and when font name versioning should be done, etc. This is a problem not unlike library ABI versioning, and it definitely needs people steering a committee of folks to draw up proper standards, but those standards can not be enforced both legally and capital F freely.
To put this in perspective, if I distributed some shell scripts under a license that said "you may freely modify and distribute these scripts, provided your versions maintain POSIX compliance", that would be daft. New versions of the script no longer being POSIX compliant would certainly make them violate a standard, and would make them buggy in many people's minds, but it shouldn't make them illegal.