Too much chance of official displeasure, even if the contraption can be legally classed as a tandem.
You would have a hard job convincing a magistrate that something which looks like a motor scooter isn't one.
Particularly when that magistrate is being told by a known and trusted traffic cop what look likes a duck and quacks like a duck is generally a duck.
The retailer/importer would be nowhere to be seen at this point, so it would be up to the user to go to the time and considerable legal expense of proving the scooter is a push bike.
Always assuming the retailer/importer is not full of bull.
It's a bit of a legal minefield, so it may be this scooter can not be classified as a push bike.