Well I guess that puts a whole new perspective on things. I didn't realize that some stove say that. So yeah, a better quality stove is a must if you are planning on leaving it. Also, make sure that you aren't fudging the clearance factors to flammables.LOL people ride around in "bombs" every day, and let them run, unattended, in cold weather, all the time.
Helping out here, and having to look up stove manuals, there are some, usually,if not all, cheaper stoves, that says right in the manual, "DO not run stove unattended". I would never own such a device!