A bit too much for me to read all of it but, from what I did read, he has a point.
To sum it up, there are hardcore players, casual players and varying degrees in between. You cannot possibly cater for all of them with a fixed level of difficulty, even if it does scale with your characters abilities. Also, your combat rating is for your combat ship which is probably pimped to the hilt with engineering mods, not a poorly armed and set up cargo hauler that would probably have trouble killing a sitting duck.
A difficulty slider makes sense for offline games and it would make sense for solo or group play if the solo player or group owner sets the pace. We could then experience the level of difficulty we enjoy without it interfering with anyone else. Only open play remains hardcore.
However, to make it fair: If you set the difficulty level lower or mission rewards, trading profits, exploration profits higher than normal, you are forced to remain in solo/group from that point on or until you delete the character and start over and cannot play in open. Leave them as default or make the game harder for yourself and you are free to change modes as you wish, (open play would then be easier than your personal preferences). This would allow players to customise the game as they would enjoy it without affecting anyone else.
Coding would be really simple: Whatever the NPC difficulty level is (it WILL be numeric), subtract the percentage in the slider from it to lower it or add the percentage to raise it, it still shows as Dangerous for example but acts like a Novice. The same goes for trading, add or subtract the percentage from the sales prices so profits are higher. Rewards for bounties and exploration is the same.
We don't all want a hardcore game, some of us just want a casual game we can enjoy playing. This is one of the reasons I wanted an offline game, we can customise offline games how we please because if we cheat, we are only trying to fool ourselves.