Read your ALPA contract. It's not the association who terminates...it's the company. The terminations take place at the company's pace.
I'm not talking about a union contract, I'm talking about United States labor law. It is illegal for a company to show disparity of treatment towards their employees. They are not permitted under law to terminate employees that are guilty of the same offense on their own schedule. If 1800 pilots are guilty of the same "terminable offense," then the company must fire all of them at once if they fire just a single one.