a legal right to enter Thailand? 😂 Nope.. It's always up to the discretion of the immigration officer if they will let you in or not. A visa (or being eligible for a visa exempt stamp) is not a guarantee for entry. If they suspect you are violating the terms of whatever entry you are trying for, they absolutely can refuse you. You don't have any rights to enter Thailand if they refuse you. It's very rare though for a person with a proper visa to be refused. It is mostly because of excessive use of tourist visas or visa exempt entries.
I have a hard time thinking otherwise too. 1900 unless they change the cost of all extensions. At some point that might happen. But not from 1.900 to 10.000.
that is the price all news outlets wrote.. That doesn't mean it's true though. It would be very weird if this would be the only extension that cost more than the 1900 baht *all* other extensions cost.