I would be a little cautious with it. Not only is it likely to have a lot of very small particulates which you won't be able to filter (from wear inside the transmission) but ATF also contains a friction modifier additive package which means the fluid actually generates a certain amount of friction - to help clutches engage, etc - as opposed to true lube oil which is 'as slippery as possible'. Adding ATF may actually lower the lubricity value of the fuel.

Then there is the minor issue that most ATF is red, which may make your fuel red, then make Smokey red if they ever sample the fuel in your tank. (The government takes tax evasion VERY seriously - as I have said before, they would rather poison you to death than have you skip out on the tax for a bottle of booze)