that may be so but most people can't have a 30 year commitment so they buy ETFs. And ETFs need a buyer for that bond to have value. if those buyers don't exist then the bond could be worth a lot less than 1000$. this is what the author was talking about with the comparison to run on the banks for bonds.
Individuals can transact directly with the federal government on shorter-duration T-Bills (4-52 weeks) through Treasury Direct.