[tagrun]

You can call in convention as many times as you want, but unfortunately, it just is not a convention. It is called theory of electrodynamics which is a well established, experimentally verified branch of physics.

What exactly is more subtle and complicated in the context of Maxwell equations? If speed of light has the anisotropy that you are describing, Maxwell equations must be incorrect. In what electromagnetic experiment has such anistropy of magnetic or electric constants have been ever observed?

You're basically saying "you haven't measured the one-way speed of light directly, so you haven't ruled it out the possibility of my exotic theory", but it is actually been ruled out by Maxwell equations a long time ago. Unless you have some experimental proof that Maxwell equations need to be modified to accommodate that elusive version of your aether, you can't claim the existence of such an anisotropy.

Physics is well connected in that you can't change one part of it (in your case, c in the context of special relatively) just because you found something that wasn't experimentally ruled out, and hope the rest of the physics (basically all massless field theories and relevant experimental results in this case) won't break.