So, in other words, there is definitely SOME OTHER FACTOR at play here. Plus, you gotta love the wording. If the baseline in the low-gun states is 1, the non-firearms murder rate could be 2.2 (nearly double) and the firearms murder rate could be 2.7 (nearly triple) - when I see general words in a study like this, it usually means some fudging is going on.
Of course it is. This research proves, beyond a shadow of a doubt, that the mere presence of guns can cause death by any means. There it is in black and white. It must be true. /sarcasm