I don't think that is what anyone on this forum is saying - specifically that the decisions being made by the UK govt re: prioritising first doses and delaying second doses will lead to better or worse results.
What I gather is being said is that it is dangerous simply to make those decisions based purely on non-clinical evidence. There are too many complexities, variables, moving parts, to make any informed decisions without clinical trials, and all the scientific scrutiny and vigour therein. In that, the only reliable information we have is that provided by ASZ and Pfizer. Outside of clinical trial, and simply throwing it out there into the public to see if it works where there is nothing but complexity, variety, and said moving parts without any of the scientific scrutiny brought by controlled clinical trial, is dangerous.
If it makes things better, then that will be largely by dint of vaguely back-of-the-envelope (nod, wiggin) guesstimated luck. And in an emergency as we have, that is the worst thing to do.
Stick to what we know - ie what is proven.