Can tower aggro not be proc'd on 1 true damage?

Died after I tried to zone their mid laner with Anivia's W while taking mid tower. Although the plan was ingenious and would have worked, there was one flaw; the tower aggro'd on me and nearly killed me. Over 1 true damage.

I feel like that's kind of messed up, Grave's Smokescreen, Trundle's Pillar and Anivia's Crystallize all have a 1 true damage value on them for the assisties.