Here is the definition of reaction time:
Reaction time is determined by each individual referee
and is described only as a period of time that is not instantaneous�
Robb certainly had control inbounds for a period of time that is not instantaneous. The only subjective part (again, this is all subjective and not some made up "clear definition of control") is what is enough "reaction" time?
There isn't a "reaction" from Levi that will prevent the TD (on his butt with Robb's arms locked around him), only the out of bounds will save him.
I'm arguing that if there is a clear TD inbound and nothing can prevent the TD from occurring, it should be a takedown.
If you believe Levi should be given some courtesy undefined amount of time to avoid the TD, regardless of how impossible it would be to achieve, and they went out of bounds before Levi could get said time then we will just have to agree to disagree.