He figured that the bees didn't like the plastic.
I think he may have been right.
Here's an example that I was shown of a frame of combs. It's just like the other beekeeper described.
It created a real problem when it came to extraction because the combs weren't supported by the foundation. So they could not be put through an extractor because they'd fall apart.
These combs would need to be extracted by crush and strain. Or just sell it as honeycombs and eat the whole thing.
I had this happen in one hive last year. The bees built the comb coming down from the wood at the top and the comb didn't touch the foundation. They had even sealed the comb on both sides. It looked like a wild comb.