There is no way to tell the difference between legitimate dc and combat logging. They look identical.
Anyone bent on cheating can game the suggested tracking system by randomly but consistently disconnecting from the game in all play situations, padding the disconnection stats so that it just looks like bad internet and the few (or many) combat logs they do get lost in the noise. They can say, "look at your stats FDEV, I get disconnected far more times jumping, hauling freight, docking, etc... than in combat." They have just proved their case to FDEV using FDEV's own stats. Your suggestion may prevent the dumbest of the group, but it will not take long for players to figure a way around it.
If you think that wouldn't happen, I have bad news for you. Look at how many players mindlessly grind credits for days, doing the most boring things imaginable. A "logging tracking system" would just create a 'logging grind' and I guarantee players would abuse it to get enough deniability to combat log whenever they needed to, just like Quince and Rhea were abused. Whole websites would pop up on how to safely 'log grind' to game the system. T-Shirts and hats would be sold... cheaters would even have fun doing it, knowing they are now immune to any action.
If there was a way to prevent it, it would already be in place, especially with how long Elite has been out. I hope I'm wrong, but I don't think so.
