Trust in PGP land is end to end. The keyservers don't matter. They are only a place to pick up keys. Your software verifies that the key is unchanged in that the fingerprint is unchanged. Otherwise it is treated as a separate key. Dead simple.
The confusion here comes from the confusion in the PyPI article about PGP. The article complained that many keys could not be found on keyservers as if that mattered.
The Debian web of trust is a good example of how this stuff actually works. Before you can submit packages to Debian you have to get an existing Debian developer to sign your PGP key. In Debian the trust flows downward from older developers to newer developers.