Police state technological solution-in-search-of-a-problem
Let me see if I've understood this right.
The reason for using biometrics in this case is to prevent someone being given a boarding pass and then handing it over to someone else, right?
But this is an old problem that has many and varied perfectly effective solutions already. And most of them cheaper and simpler and with less potential for abuse.
What is wrong with the old low-tech solution of stamping the back of their hand with an ink stamp? It needn't be an actual rubber stamp, maybe it could be one of those ink-jet printers that they use to spray use-by dates on eggshells and it could just print a bar-code on the back of your hand. (Cryptographically generated random number, so it can't be predicted or reused, of course, but that's not very hard).
Pointless, overengineered, expensive and repressive technology for its own sake, in search of government pork. Bah.