Is there policy that allows CORs not be appointed for IDIQ task orders under a certain $ threshold?
The guidance for when you can exempt a service contract (including individual task orders) from having a COR appointed is found in DFARS PGI 201.602-2(d)(v)(A). All three of the following conditons must be met:
(1) The contract will be awarded using simplified acquisition procedures;
(2) The requirement is not complex; and
(3) The contracting officer documents the file, in writing, with the specific reasons why the appointment of a COR is unnecessary.
Obviously the IDIQ (and resulting task orders) was/are not awarded using simplified acquisition procedures, therefore the conditions can't be met, sorry. Unless, you were to do a local deviation (probably more effort for that than it is worth).
Note: there was an attempt to get this part of the PGI updated and changed to include task orders and orders issued against FSS a few years back. But unfortunately it never happened.