Once we safely retrieve the raccoon, we'll relocate it to a humane location, remove the contaminated insulation, disinfect the attic area, reinsulate the attic with blown-in cellulose insulation, and seal up the access point with sturdy metal flashing.
We installed a one-way over the main access point and enclosed the area temporarily with hardware cloth. We also placed several baited traps nearby. The one-way allows the raccoon to safely exit the attic, but is designed to prevent it from getting back in.
Once I removed the nest, the homeowner mentioned that he will remove the branch the nest was attached to on his own.