The '"debunking" is merely the post office's statement on the matter. And merely a general statement that say mailboxes are removed for low use. No evidence the person making the statement has any information over the Portland situation in particular.
If the postal service can be distrusted with absolutely no evidence simply because a lot of postal workers are Biden supporters, I am allowed to be skeptical of the post office due to actual, proven wrongdoing by the postmaster general and his policies.