The UCI banned some handlebars that were regarded as too far forward, they've banned elbows being too high, they've banned handlebars pointing slightly inwards. They'll ban anything that's even slightly out the ordinary and with no reasons given.
I mean, I kinda get it, it's a traditional upright bicycle race where they want the human factor to dominate. But somewhere in there's a ~65% performance improvement they are leaving on the table (that is the difference in the "1 hour distance record" between traditional and fully faired recumbents).