I guess we would have to define what "should do" means to everyone. Certainly, it works for its intended purpose.
But having a toggle for real-time denoising in Render Setup and having a checkbox for denoising in the VFB while in IR (albeit grayed-out) with no connection between them is a missed opportunity. Having to go into Reder Setup while in IR to enable/disable it is a task that can take more than 10 seconds, with 3ds Max lagging and all.
So for me also, it "should" turn real-time denoising on/off, in addition to Hiqh-quality denoising for final images.