tomBitonti
Hero
That definition of -ist helps not at all; gamist could mean someone who likes gaming, or who hates it.
Except that, for usual language usage (meaning, everyday talk), those meanings are the ones that most people will use.
You could preface a discussion with a qualifier, say, "A discussion of the term Gamist, as used by person X in their paper Y." Then you can have Gamist mean what X had it mean.
Otherwise, you are stuck with everyday usage.
I'd say, since the context of the initial question is the enworld boards, and folks here use Gamist in both the GNS sense, and in the everyday usage sense, that it would be fair to interpret the initial question as "Hey, enworld users, what do you usually mean when you write Gamist?" That provides room for both the everyday meaning and the specific GNS meaning.
TomB