What about if you are telling a story in the present tense as people might do colloquially. Eg "I go to the big room and sit down in my favourite chair when suddenly I remember..."
If we started allowing such interpretations, then we would have no way to teach the grammar. I understand that it can work in such a way, but accepting it would be very harmful to the learners.
Conversely, can "Idę do najmniejszego pokoju." be used as in English as a euphemism for "I am going to the bathroom"?
Never heard anything like that. Neither in Polish nor in English ;)
Euphemism for going to the bathroom... the first one that comes to my mind is "Idę tam, gdzie król chodzi piechotą" (I am going where the king goes on foot). English Wiktionary lists something pretty similar.
When I was a child people used to say "I'm going to sit on the throne" but I haven't heard that expression for years