He clearly has real world working experience. But any resume that is missing out on even a couple of months worth of experience signals a red flag to me.
This is the culture of corporate America. Holes are EXTREMELY bad in your resume. Period.
Is it a fear of non-compliance?
Holes in a resume are bad because most people who look at resumes think that holes are a bad thing. Its simply the bias that exists in most jobs (that I've come across... anyway)
you are a lazy piece of shit
you were incarcerated for bank robbery
you were on the run from the Feds living in Argentina
you went to Pakistan to attend a Jihadist training course (BTEC-diploma)
you were kidnapped by aliens and given daily anal probes (that never impresses the interviewers)
you were being trained in cutting-edge industrial espionage techniques by a rival company of the interviewer
you spent the time going through sex-reassignment procedures and changed your name to Gladys
you worked for the NSA
The average interviewer will think all of the above and more in the space of two milliseconds, whether any of these delusional thoughts have any basis in reality.