Chemo can't use Poison from two squares away because Giant Reach says:

When this character is given an action that includes a close combat attack, all squares within a range of 2 and line of fire are considered adjacent.

Poison is not an action that includes a close combat attack. Chemo would not be adjacent to Thanos for the sake of Poison, if he was two squares away; however, if Chemo then was given a Close Combat Action for a Close Combat Attack, he would be adjacent to Thanos from two squares away.

You're not reading what I am saying; you just repeated what I actually wrote.

Chemo *IS* adjacent to Thanos for Close Combat purposes. But for poison, and many other things, he is not.

Then I don't understand what the "No, no, no" from your post was meant to mean, since it seems you are agreeing with me.

If a Giant makes an attack against Thanos from two squares away while Thanos has his Defense SP, Thanos will not ignore the damage.