The middle option: they want to hear the case and haven't made up their mind yet.
It is basically a functional solution to have the CoA decision vacated once transfer is granted. The CoA opinion is precedential (basically) from the moment it is published. If that decision wasn't vacated, you could have parties out there using it for authority while the ISC decides whether it should be or not.
That'd be bad.
Rarely, but sometimes, they adopt a CoA opinion in whole or in part. It is rare, though, because if each justice immediately and completely agreed with the CoA opinion, then they wouldn't need to grant transfer.
The most we can read into the transfer grant is that a majority of justices believe there are one or more issues worthy of being addressed by the ISC.
If this case stands, it isn't exactly constitutional carry. If police have RAS of a crime, they can detain the suspect, determine that the suspect should not have a firearm, and then arrest them for CHWOL (Carrying a Handgun With Out a License).
With constitutional carry, that crime would no longer exist.
The display of a firearm would not - standing alone - provide the RAS necessary to detain, if this case stands.
A note of caution: the interaction between this guy and police is what the State is making the focus. The State's position is that the interaction was voluntary, that there was no detention of Pinner. The problem came when Pinner denied he had a firearm, then began acting nervously. If an officer can point to reasons that he is concerned about his safety, he can disarm even a legal possessor of a firearm.
If the officer searched and found the handgun based on a reasonable concern for his safety, even in a voluntary interaction, and found the wrongly-carried handgun in the process, then this case gets decided in such a way that really avoids what the CoA decided.
