Well, it was not wise from him to do such a thing, it is oftenly misunderstood that gaps arent allowed by IRCC and that they will persecute anyone who has them, well its not like that at all.
IRCC doesnt want any unjustified gaps and specially the ones between work years not between graduating and starting a job. They know that peiple arent suppised to work straight out of college and that unemployment anywehre from a month to a year is allowed and actually that was my case, i was unemployed for 1 year and 4 months after graduation and just filled that in my personal history as unemployment.
Plus they dont care if you prove the work experience in your personal histroy or not, there is no need to prove anything there.
Anyways, I cant say definelty if they will ask about it or not, what I know is that the work permit and the express entry applications are treated seperately and dont intertwine BUT i cant be definitive and say that things like declaring stuff that didnt happen will come up or not