That's a good point. But I would still include a check for OS's that I know support it. This means it wouldn't work on OS's without first explicitly allowing it.

I view this as a feature and not a bug. There's a good chance there are other things to consider when a new OS adds pledge or unveil, and this gives the developer a chance to test support on the new OS before anyone uses it.

Basically, I disagree with the article that you want to implement this in Python in a completely OS agnostic manner.