They don't always require Equity ASM's but if an ASM is not required/hired, I don't believe you can acrue EMC points for serving as a non-Equity ASM. Just my opinion...
And apparently in LORT EMC point can only be accrued if there is an equity ASM. So a PA acting as a non-union ASM can't accrue points, but might very well get bumped up to an equity contract in later seasons.
My $0.02 - a theatre i PA'd for gave me my card at age 23 (i never even looked into EMC) and i haven't had a problem finding LORT work. But that could be very different in another region.
I'm not convinced that accumulating EMC credits shows employers you are serious about the career path. You could be extremely serious about professionally stage managing in non-AEA venues. In that situation it would be a waste of time, money, and effort. And worse, a non-AEA producer might think that you aren't interested.