Can't file an EZ for 2015 as the plan covered one non-owner for some portion of the year. Namely 1/1 until the employee was paid out.
If no new employer enter he can file EZ for 2016.
I'm just guessing, that an auditor that challenges this in the first place is unlikely to be swayed by your last point. They might just say, "Then that's what you should have done."
But I revert to my original theme that I have found most auditors to be fairly reasonable, and doubt that they would give you a hard time on this anyway.
And my opinion and $50.00 will get you a 2 oz. espresso at Starbucks...