Over the last 10 years I've ordered, too, many LPs from outside of the EU. Only 2 parcels have ever incurred import duty, even though all of them have been above the threshold.
It's kind of annoying to have to pay VAT and charges that are more than the record cost. But on balance spread across the number of records I've imported it's negligible.
The guy's attitude was very much off, but he was probably having a worse day than the OP.
I find it best to have a little rant and then get on with my life.