The idea behind Scubapro's splined fitting is to prevent customers from removing them. You can tighten them with a pair of pliers, just wrap the fitting in cloth and proceed carefully so you don't mar the chrome finish.
For a very brief period of time I dove with finger tight second stages on the then trendy theory that doing so would allow you to swap second stages with a deco bottle, etc if needed. The fact is it is virtually never needed and could be covered by taking a suitably sized wrench in a pocket - something like the scuba concepts wrench - a lightweight stamped metal wrench.
The problem with finger tight is that it has the potential to become un-tight during the dive and in the course of a couple gas switches it is possible to loosen the second stage to the point where the swivel o-ring is unsupported and fails. This kind of failure usually results in about 1/4 to 1/3rd of the 0-ring being blown out with a large leak resulting. Lots and lots of bubbles and no way to stop them other than shutting off the post with that reg on it - a potentially very significant problem for a single tank diver at depth. I dive doubles and have valves on my manifold but I prefer not to have to use them to isolate a failure. After isolating this particular failure at about 150', I decided finger tight was a bad idea regardless of what I read on the internet.
From the tech perspective, you normally assemble the second stages to the LP hoses finger tight to facilitate instaqlling an in-line adjustment tool on one, then the other to adjust the orifices. Then, once adjusted, you remove the tool, re-install the second stage and tighten the LP hose fitting. My suspicion is that the tech got interupted post testing/pre tightening and forgot about it. Not a major error and one that is easily fixed - but do not leave them only finger tight.
