Can a spice grinder be used for coffee permanently?
The Cuisinart SG-10 spice grinder it designed to grind soft and hard spices. There is no reason why it couldn't do coffee

The SG-10 manual even mentions nutmeg, which is significantly tougher than coffee

Many coffee "professionals" like the burr grind (like a pepper grinder), compared to the rotary blade grind (like a small food processor), but either will work fine

Also, many people grind spices in rotary blade coffee grinders, so it comes down to which style of grinding you like

One issue with rotary ground coffee is the inconsistency of grind size. There will be too many fine particles that will leech out of the coffee holding/filter mechanism. If you don't want solid particles in your coffee use a burr grinder