The decision is correct. The laws have changed.
The Laws have historically required the bat or part of the batsman's body to be grounded behind the popping crease. In this sense the law meant physically grounded - actually touching the ground at all times.
Since 2013, the laws extended the meaning of grounded to also mean a batsman's foot after having stepped behind the popping crease and continued moving in the same direction, even if not touching the ground itself. When sprinting, there are moments where both feet are temporarily off the ground. This change removed the element of luck so that a batsman couldn't be out if the wicket happened to be put down at the wrong moment in their step.
In 2017, the MCC conducted a large number of changes to the laws. One such change was to Law 30, Batsman out of his/her ground (previously numbered 29) which extended the definition of grounded to include a bat which had bounced or had left the hand of the batsman after being grounded.
The net result is that provided the batsman continues moving into their ground, they will be considered inside their ground if they get something (bat or body) grounded beyond the crease, regardless of subsequently lifting it off the actual ground.
See Law 30.1.2 for the full text explained in the previous paragraph.