Not to spoil the mood, but I read over the rule it says it "fires using the same rules as a fire thrower,but with the profile and differences given below". If Army book trumps Rule book does that mean it trumps auto panic rule of fire throwers. It just says it fires as on, not that it is one.
I think if that was the case as the rule says with the following differences it would have listed that it did not cause a panic check as that would be a difference from the BRB.
I once Panic'd a Chaos Marauder horde off the board.... It was THE BEST. So Glad that they kept it this way.