You should be OK. The younger bimacs seem to ink with a thick ink, not one that causes general cloudiness. And you have a protein skimmer, which is the best ink remover.
But in the future, keep some salt water made up so you can do a water change if you have to - at least a 10% change. You want the salt water to age a bit - don't use it right away after you've mixed it - give it 5 or 6 hours, or even a half day.
Why did he ink? You started him in some way. If your moonlight is red, your octopus will not be able to see that light. All octo owners need to get in the habit of approaching the tank in the same way each time and not make sudden movements. I once made the mistake of thinking my bimac,who was glued to the glass, was awake. She was asleep, and when I turned on the light, there was a big inking and running for cover.l