It could be both Reader A and Reader B, otherwise they would've not written the conclusion as they did but they would've kept it on bio/scientific terms only. The goal of the paper is to show the need for money.
The authors make their undoubtfully well researched points, and make a recommendation which is aimed at easing the second wave (and the impact of future viruses) through policies, regulatory agencies, governments, pharmaceutical companies, and therefore through lots of money. The fact that the article is published on a journal of technical nature does not exclude that this is a paper aimed at asking for money in the least. Actually, this is a fundamental part of how things are done: the first step is usually to convince your peers of the necessity for funding research, and it seems that the authors do their job in that. There is nothing wrong with that, and it does not remove anything from the scientific research (if anything, it might prove to other researchers that the scientific research is of fundamental importance). Then you need to convince whoever wants to pay, and again the authors do that (albeit writing their statement just at the end).
"Huge price tag" is a personal evaluation; personally, I think that a few billions for a Covid-19 vaccine would be very be well worth it. I made no evaluation on the price tag until now, and I made no criticism - or praise - of the argument proposed by the authors which are no doubt experts in their subject.
I am still puzzled.