I live in an old house (70 plus years old) with wood walls and ceilings and 1/4" sheetrock coverage. Condensation line back up caused water leak and stain on ceiling approximately 4'X4' requiring repair. Insurance company sent (ServiceMaster) for "water remediation" involving 5 days of very loud industrial fans and dehumidifiers after which instruments suggested residual wall/ceiling dampness and need for a "more invasive" approach (which would also require lead and asbestos testing due to age of house.) I politely told them to pack up their stuff and called my insurance company informing them of my action. I have a inexpensive moisture meter and can detect some residual dampness in attic insulation and wood ceiling but for the life of me do not understand why this would be a future issue due to West Texas dryness, heat and air circulation in attic. Am I wrong?

No if it dries quickly. I would recommend removing and replacing the attic insulation if it is the blown in kind. Once that gets wet it looses its r-value and doesn't work as well.

To me I would do what the insurance company wanted / suggested but I have only had one home insurance claim due to a water leak. Def no expert. I had no issue with ServPro destorying my walls and running loud machines. We were given a hotel for a week. When we sold our house about 2 years ago, we had all the support showing the issue was properly / fully remediated.

I would also have sent them away.

Put bleach in your line very month during the summer and it prevents the clogging.