I'm never a fan of playing players out of position. Sure Clyne, Gomez and Trent could do a 'job' at LB but it'd be negative and would stop the whipping balls in from the left.Besides, Gomez and Clyne can both play at LB, Trent probably too – that's not even taking Milner into account. There are lots of options at FB at the moment.
Whereas now that we switched to the system with 2 sitting midfielders, that midfield looks awfully thin – with Hendo injured we are now down to just Gini, Can and Milner for the busy festive period. Even when everyone is fit, Hendo can only play 1 game a week to minimize the risk of inflammation in his heel, Milner doesn't have the energy any more for 2 games per week, Can nowadays turns up only whenever he feels like it... so basically Gini is the most consistent and physically durable midfielder we have. If Can leaves, I recon we need at least one more in addition to Keita, just to account for aging of Milner and Hendo's condition.
Beyond Robbo, I trust Moreno as much as I trust Ming to have an error free game. Milly probably hasnt got the legs for LB anymore.
Hence why I personally would like another.
By your logic Trent could also play CM (his u18 position).