My thoughts on the updated matter are:
I knew Sony would come out pretty quickly and tell everyone they'll be getting the refund, not refunding them would be the worst move Sony could make at a time where they are still struggling overall as a company but are actually making good ground to get themselves out of the mess.
The whole situation was brought on from a random tech support guy, he just said exactly what his script would have told him to say regarding anything with pre-orders and refunds, and that is that no refund is given on pre-order items.
BUT, what I don't understand is why it even got to a tech support guy anyway or why no memo was sent to support teams telling them about the $10 refund.
In an almost fully connected world, where billions of people can interact with each other at the click of a button, Sony MUST have known that this would make the rounds, VERY quick, if they seriously thought that this wouldn't have spread like wildfire, they are insane.
The second the decision was made to drop the price, an announcement should have been made regarding both the price drop and the refund of the difference to PSN pre-order customers, if you wanted to be extra careful, send a memo to the support teams informing them of the $10 refund so they can relay that information accurately to customers.
Sony have just created bad PR (however minor now) that was completely avoidable and not only completely avoidable but easily avoidable.
It's all well and good to say that the tech support guy didn't have authority to make a decision but support is the first point of contact for a company, the failings were not with the tech support guy but Sony as a whole for not properly informing support staff - Assuming that they planned the $10 refund all along.
If they weren't considering the refunds at all, thinking that nothing would come of it, I would almost write them off as having no common sense.