You're entirely correct. Dorian has ignored the warning signs from everyone. He's the strength of the title and does control certain aspects of the pack, but is ultimately a co-alpha at best and a figurehead at worst. He has lost control of at least the business side of the operation. If he managed to retake control of everything, the pack would be financially devastated but could eventually recover. Ethan healing him has cleared his mind. Dorian may not be able to return to the person he was at 25 when he took over the pack, but to me it would be possible for him to move back in that direction. If there wasn't the known problem hanging in the air.
What's been established about the use of Silver Nitrate on wolves is it causes persistent pain, headaches, misplace aggression, and impaired judgement. Silver poisoning could cause all the same symptoms. Dorian's had been told for years by the packs primary doctor that his blood test was clean of the drug and it was a remnant of being stabbed with silver when he was 15. Now depending on when he started receiving the poison, if it was gradually increased over time, some of the effects like the impaired judgement wouldn't be as noticeable to him. Kind of like the science experiment of a frog with hot water vs. slowly increasing the heat. Which one kills the frog?
The next chapter has a reference to the time frame. I could probably give that away now without affecting next Monday's release, but I'll hold off.