Beeboy, in our area, Southern US, I consider the shb more of a threat the mites. You are so correct: the beetles in jail are confined until the beekeepers open the hive. The beetles then make a jail break, a week later, larva and slimed comb.
The slime is actually a yeast secreted by the beetle larva emits an odor which is an attractment to shb.
The second attack you describe is on the money also. I have caught 20 beetles in a single trap in a single night. I figure I catch maybe 50% at most.
The freeze gun is deadly on the small hive beetle, my freeze gun is a can of freeze spray available on Amazon or at office supply stores. At minus 62F, non flammable, non toxic gas is controlled by a trigger and precisely aimed by directing a small tube, like on wd40 without harm to a bee 1/2 inch away. It the same spray often used in doctors office to freeze skin aberrations and to spray clean computer chips.
I buy the cans by the case of 24. I?m not supposed to state price but I can say, the spray can is very affordable.
Actually, it?s a blast to spray the beetles. My bees seemed trained to it and get out of the way so I have a clear shot at a beetle that hides deep in a cell. That beetle is a goner. I like it, so do my bees. The bees don?t seem to mind one little bit.