[deanmontague]

What would he have gained from replying to hussein?

A fight, a resolution, a hug? a friend?

No. he'd have gained nothing.

why invest energy into something where the end-game is pointless?

At the end of the day, Husseins issue with Lewis can't be rectified because it comes from a place of personal hatred and jealousy - nothing has particularly happened between either of them for him to have so much dislike towards him.

He said he might not be able to keep his cool, and he kept his cool, kudos to him.
And if you watch the show back you can hear lewis say 'what is zoe doing' she was uncontrollable.

If anything, it takes the bigger man to not react to such a goading gimp