Of what i read the manufacturer has said they can't guarantee it will still be useful against Covid if the dose is given so late.
But, as BB put it; the numbers and the showing probably counts more to those with their necks on the line, than the lives they're potentially risking.
"The announcement caused controversy, however, and Pfizer and BioNTech warned that two doses of their vaccine were required for maximum protection against Covid and that they did not have evidence that the first dose alone offered protection after three weeks."
https://www.theguardian.com/society/...f-second-doses