A bit late to the party and I am aware of what handicap generally means, but in this context I meant this term in combination with the fact that this person sup

A bit late to the party and I am aware of what handicap generally means, but in this context I meant this term in combination with the fact that this person supposedly can't understand metaphors is disabled for the particular activity of understanding metaphors. If your brain can't understand metaphors, you could say this common ability for you is disabled. Also since most people do understand metaphors it can be interpreted that the poster is calling them lower in intelligence than most people which could fall into the zone of intellectually disabled.