There is no need for a PCB on that if you use it as intended. The user is supposed to open the can and charge the cells in a cell charger (or two) -- there is no pack charger included. If your cell charger has independent channels it will keep them balanced or at least fully charged. There is no more danger than charging 18650s for your flashlights, but you would want to use protected cells.

It could get scary if someone tried to hook a pack charger up to the battery holder/dumb pack, but they make it difficult to to this by accident. If you look at the pics (and if they are accurate): typically the male connector is on the lighthead - they put it on the pack. To use a pack charger someone would first have to make an adapter. Someone with enough smarts to do that may wonder WHY they need to do that. In that case, yea you'd want a PCB (or a low deductible).

Advantages to a dumb pack are that it costs as little as $20 to replace the cells and it is very easy to monitor cell health. Being all enclosed as it is, it is a very nifty holder for a dumb pack.

The one pic of the open pack looks like the end screws on like a lid AND has 2 screws thru the lid into the housing. It would be tedious to undo those for every charge. EDIT: No, those are just alignment pins sticking up from the floor so you dont insert the cells rotated 45*.