Because it was “desirable”

The covid19 fraud/psyop was allowable on a whim.

42 USC 247d-6d(b)(6) Factors to be considered In deciding whether and under what circumstances or conditions to issue a declaration under paragraph (1) with respect to a covered countermeasure, the Secretary shall consider the desirability of encouraging the design, development, clinical testing or investigation, manufacture, labeling, distribution, formulation, packaging, marketing, promotion, sale, purchase, donation, dispensing, prescribing, administration, licensing, and use of such countermeasure.

“Desirability” is a non-physical characteristic, and not subject to any standard of evidence or fact-finding process.

“Desirability of encouraging” also begs the questions: desirability for whom, of encouraging the manufacture and use of countermeasures intended to induce which effects?

Source: (3) No one can be found in legal violation of a rule they were never required to comply with, nor can anyone be found to have failed to meet an evidentiary standard they were never required to meet.