It's an aspect of that whole incident that a lot of people of overlooking. Shelvey did f*** all wrong, Lansbury got him sent off and he should be thoroughly ashamed of himself for that.
He kicked out in retaliation. It's been a red card offence for as long as I can remember - Beckham on Simeone in '98, Vieira on van Nistelrooy etc.
Do find it staggering however that a penalty was given for what was essentially a foul on Shelvey in the first instance. Incredible that Lansbury went unpunished.