^^^Yes, he CAN leave the fuel rails/injectors intact, and in place, and just disconnect the injector electrical connectors, the fuel line into the fuel rail, the MAP sensor electical connector, any EVAP/PCV, etc. connections at the front and side of the manifold/TB, and whatever vacuum and emissions tubing connectors the Tahoe has at the back of the manifold.
I WOULD get new intake manifold gaskets (there are 8 individual EPDM type material rectangular 'gaskets') and install them while the manifold is off, even though many say they can be reused.
But why not, since they are not too terribly expensive, and it is good preventative maintenance while one is doing all of that work anyway?
I also would clean out the intake and throttle body while it is off of the truck as well.