The company should publish a "practice training letter" along with the practice bid. A lot of ANC FOs would have seen the order and elected to bid SO.

There is another issue. Junior pilots who are not in training yet are allowed to bid Hong Kong while senior pilots who are in 727 FO ITU cannot because of contract paragraph: 24.E.2.
Bidding Restrictions on Subsequent Postings
During the time a pilot is in ITU training, he shall not be awarded a crew status that he could have been awarded on the posting containing the crew position for which he presently is in training, or on a subsequent posting that closed prior to the start of his training.

This restriction only applies to pilots who are in ITU. If the company excessed in "reverse seniority order" these pilots would not be in training and thus allowed to bid HK.