1. Not sure where I implied carbon would replace bio filtration? But hey, w/e. As far as bio media is concerned, it's highly doubtful there is no bacteria available to process ammonia, unless the OP went through the process of painstakingly bleaching, salting, or drying out the media for a few days. Other than that, it's mostly
still there. But that isn't what she said. She said she removed the problem pvc and washed the gravel. No worries there (assuming common sense was used).
2. Cloudy water due to breakdown of the glue (per OPs post) is a situation that WOULD be helped by carbon. Not sure anyone can really argue with that. Milky white water would imply a chemical reaction in the water to me...
3. Suggestion for mechanical filtration is based on the particulate that may be in the tank from the Loctite glue breakdown. This lead to my comment about the future - pvc should be held together with primer and pvc glue. It's the easiest and safest method. While Loctite epoxy is safe, it appears that there was a problem with this application. So for safety's sake in the future, etc, etc.
4. Suggesting using fish to cycle a tank is archaic and one of the worst ideas in this thread (in my opinion, of course). In the event that the tank and filtration was stripped clean or in a new setup, adding organic material to rot or even better, ammonia dosing is the fastest, safest, and most humane process.
Congratulations on your 36 years of fish keeping. They seem very important to you. One day I'll have 36 years, and they'll be important to me. But by then you'll have 46, and you'll be more proud of them.