Is it legally permissible for an architect to issue a negative certificate?

This is completely dependent upon the specific circumstances that exist. Three questions essentially govern this matter:

(1) Are there any circumstances when it is permissible for any architect to issue such a certificate?

(2) If yes, is the contractor obliged to make payment to the employer?

(3) If yes, do provisions about notices work in reverse?

Based on previous legal precedent, the answers are “yes”, “no”, and thus the third question is “no” by definition.