I think the postal service is technically some weird in-between where its neither fully a part of the federal government but also not fully a wholly owned subsidiary of the federal government
That is correct. While not employed by the federal government, they do deliver the mail on behalf of the government and there are federal laws against obstructing the delivery of that mail.
The difference is that one of them is officially acting on behalf of the federal government and one is just a bigoted private citizen.
The postal worker has violated federal law and should be held accountable legally.
The baker is a shitty person and was publicly called out for it but not legally punished.
I think the postal service is technically some weird in-between where its neither fully a part of the federal government but also not fully a wholly owned subsidiary of the federal government
That is correct. While not employed by the federal government, they do deliver the mail on behalf of the government and there are federal laws against obstructing the delivery of that mail.