'sat' for 'sitting'

This is from a story about a couple whose first meeting was on an aeroplane:

"Their first date was sat next to each other on the plane, and after reaching their destination the loved up pair kept in touch via social media and Skype."

There is a great deal wrong with this sentence, and I would recast it as

"They first met when seated/sitting next to one another on the plane ..."

but I want to focus on 'sat next to each other'.

Standard British English would have 'sitting next', and I think this still applies in US English.

The use of 'sat' for 'sitting' used to be a feature of northern grammar, but is becoming increasingly prevalent and is now, apparently, sanctioned in print as standard.