It is exactly because of the elevated acetyl-carnitine-induced free-radical activity that an antioxidant such as alpha lipoic acid is usually recommended for simultaneous consumption. As a matter of fact, Life Extension Foundation's premier product for mitochondrial protection, Mitochondrial Energy Optimizer, combines two advanced carnitine forms (acetyl-carnitine-HCL and acetyl-carnitine-arginate dihydrochloride) and r-lipoic-acid, amongst others. So LEF basically combined potent antioxidants with ALCAR and acetyl-carntine-arginate, in line with the classical recommendation.
In any case, I would appreciate a reference of any Life Extension Foundation recommendation for separating carnitine and antioxidants. That would help clarify a lot of things.