i've heard similar warnings against clear-coating a raw frame; that it won't hold up for more than a year or two, and that it will begin to rust under the clearcoat, especially where there are hand or finger-prints.

i've been riding a raw steel frame with no coating at all for two years. it's totally fine and looks great! it does develop light surface rust over time and i work it over with steel wool every 3-4 months to keep it clean.