Not a big deal to me personally on a players level machine. I don't drop quarters into my machines.
I think what he means is "if you replaced the coin mech, it would work fine with quarters. But why do you want to do that?"
I don't know that particular machine, but it's common from that era to not have a "free play" option. Easy work around if you want, so it's not a big deal.
But just to clarify, there should be a "start" button on the front of the machine. If that is missing somehow, you need to see why. But if we are just talking about adding credits to the machine - the lack of a coin mech wouldn't be a make/break decision in my mind.