Yes, that is true as well. I wrongly assumed that just like how I expect the VPS host to safely overwrite storage of when the VPS is deleted/decommissioned that

Yes, that is true as well. I wrongly assumed that just like how I expect the VPS host to safely overwrite storage of when the VPS is deleted/decommissioned that they would automatically remove PTR records from their DNS servers relating to that VPS. There is, after all, absolutely no reason why they shouldn’t delete the PTR records that a customer created for an IP address when that IP address is no longer in control of the customer. But indeed the whole ordeal would have been avoided had I myself gone and deleted the PTR before I removed the VPS.