Advice. Normal residential homeowner with 500gal propane tank for generator, BUT also line to house with a shutoff valve

Hello!

I have a propane tank on my property mainly used for my generac. I live in a normal neighborhood covered in big tall trees and above ground power lines. They come down a lot and the power goes out so the two together are pretty neat. The original owner had the system professionally installed in Nov of 99 because he was prepping for Y2K (lol). There is also a line to the house with a shut off... it has always been off.

I just called a propane company (suburban propane) to get it filled to make sure I'm ready for the next time power goes out cause its usually out for at least 18 hours and this is the 2nd year I've ran it for that long... they wanted to first inspect the tank and lines, which is fine. Once I told them about the line to the house they kinda freaked and said they would absolutely need to cap it off... cause natural gas appliances cant run propane and its a fire risk.

I'm cool with that- BUT i want to make sure before I have the propane company come cap it off. I kind of got weird vibes cause initially inspections were going to be free, but once the service manager called me even prior to telling him about the house line he mentioned a few surprise fees. I just want to make sure I do what's best for my system.

Who would I contact next to come inspect the outside lines AND the inside hookup To see if it truly needs to be capped, or if it is a safe and viable set up? Is there a better subreddit for this question?

Thanks everyone.