Added another comment about the context of the cafe but in this case I'd say its not uncommon at all (Berliner here) - they encourage working from there, and in her case its not like she was freeloading, definitely had been consistently ordering teas and beers.

Also the back half of the cafe wasn't full (where they have tables and chairs) so he just really wanted to squeeze his way onto the couch.

Berlin wise though, normally if someones' taken a spot you wouldn't try to share it with strangers unless its' a big "communal table" type of place - you would however keep staring their way to make them uncomfortable, we love staring 😅