It depends on whether Lee does not invade Pa., because he is, m sending reinforcements to the East. If he is, then he necessarily, must pull back to defend Richmond behind the Rappahannock.
I he is not going to invade Pa., or send reinforcements west, the Shenandoah Valley is only a protected invasion route North towards Washington City and, perhaps Baltimore. and if he is using it as a threat to invade he does not need to base his whole army there. He needs to be back in his old lines, where he is closer to supply line.
So, No, The Rappahannock is the place he needs to be.