How come Rav Shach must be called r shach otherwise your a lubavithcher hater, but shach in shulchan aruch shach goes by shach (the shach says)
For the same reason we don’t refer to Rav Chofetz Chaim.
When we refer to a name of a Rav, we use an honorific. If we refer to a person by his magnum opus (as in the example you brought), we just refer to the work without adding any titles.
The Wolf