"At $15 billion that means they think the CEV will take 60,000 person-years of work to design and test. If development takes 5 years, that means they expect they will need about 12,000 workers."

If you think you need 12,000 workers, then designing and building paperclip gets pretty expensive.
The question is, are you really looking for a nice job's program for highly educated and well paid employees.
If CEV is going to cost 15 billion, then it's going nowhere. Period. End of story.
If Rutan can build a sub-orbital vehicle for less than 50 million, then a CEV should be less than couple billion to develop, even by an inefficent Lockmart or Boeing.