Gauging ability to operate under pressure is valuable too...ever tried to fix a bug on a device that was supposed to ship yesterday, under the pressure of the entirety of the hierarchy above you all the way up to the CxO?
It helps to know if the candidate you hire will handle that, or fall apart just when you need him/her to do the job he/she is paid for.
Um, you really can't interview for that person, thanks. That person is someone who is already in your company and gets promoted to "trusted lieutenant". Promotion to "completely trusted lieutenant" is only awarded posthumously. :)
If that kind of situation is happening more than once in a blue moon, something is very wrong at your company.
As an organisation you have to decide on what you want. The developers who can handle high stress situations are rarely the most skilled developers.
If you are hiring for a high stress environment then you need to focus upon candidates who can handle stressful environments over candidates who write really good software.
On the other hand most environments are not high stress.
For what it's worth, the author included this footnote about what you mentioned.
"1. The stress of interviewing seems to be different than the stress of performing a job. None of the people we've spoken to who do poorly in interviews report problems performing under deadlines at work, or when a website is down and there's pressure to get it back up."
It helps to know if the candidate you hire will handle that, or fall apart just when you need him/her to do the job he/she is paid for.