Yes, the permit can be held for up to 4 years, it's not an automatic 4 year extension. Depends on the particular circumstances of each application. And the reasons for putting a permit on hold are very narrow - being sent abroad by your Swiss employer, military service or further education. Any other reason starts off as a default "no" answer so you'd have to make a very good case to change that to a "yes, okay".
You need to research whether you/he are specialised enough to keep your jobs if the quota limit for EU nationals comes in next February. Priority will be given to Swiss and other nationals already living here so if you stay away for another 12-18 months it would be a new application under those conditions. I would also talk to your/his employer to explain your concerns, given the length of time you've been out of the country already and the possibility of a quota system being applied to EU nationals. They haven't said what the hiring criteria would be, but I assume it will be similar to the non-EU one in this link:
https://www.sem.admin.ch/sem/en/home...zulassung.html
I believe they need to put a bill to the Swiss parliament by the end of this month to meet the timeline laid out in the 2014 referendum so keep checking swissinfo.ch, thelocal.ch and of course here on the forum for news.