He probably also doesn't want to need glasses in court so he has the biggest screen so each sentence can be in font size 48 and still fit on one screen.
More than likely there isn't anything on the screen unless the lawyers put something on for him to say which he will ignore anyways.
He's functionally illiterate. There's video of an old deposition of him from before he was President where he's asked to read some materials and his lawyer keeps trying to put a stop to it because it's clear he basically can't read.
They also knew they shouldn't give him a keyboard because he'd crash that thing in no time while bragging about how much he knows about IT and all the FANG tech leads who told him how knowledgeable he is.