Feat: Dragon Storm
After all friendly models have completed their activations this turn, each warbeast in Thagroshʼs battlegroup that is in his control
area can make a full advance followed by one normal melee attack. Completely resolve each modelʼs movement and attack
before moving on to the next model.
No, Thagrosh feat doesn't affect him because he is not a Warbeast.
And Warbeasts cannot be Forced outside of their activation so they cannot be Forced during the feat move + attack because this is not an activation.