That would be unprofessional if they will change their mind after making a decision to close the business.
No, I think it's something perfectly normal. I have seen some services do this kind of thing before, and they are still running business well as usual after making a U-Turn. One of the services I know was purse.io who had initial decided to shut down their business but then
reconsidered to continue operating after some time
What always causes this is if the project was sold to another management just like how Coinmarketcap was sold to Cz Binance because it will take a lot of time before project devs would decide to close down a project.
Taking the U-turn can't just happen like that.