Great post and I'm glad you included the quotations because that would answer the stereotype not the technical.
Technically, the difference between a hardcore gamer and casual gamer depends on time spent in a set time period. That is the only difference.
But considering you used quotations we are dealing with the stereotypes of what these groups are and thus this makes a hell of a lot of sense. I personally don't give much thought to stereotypes and preconceptions about certain groups because I deal with technicalities and facts. But if we were to discuss the stereotypes of the groups then this would be quite a good analysis which is why I give kudos to you. Well thought out but I'm sure the supposed hardcore gamers are going to feel slightly offended by it. Makes them sound elitist twenty somethings who haven't come out of their mom's basement in over 10 years. Of course, the way they describe their stereotype, this is how they make themselves sound.
