Regardless of the semantics, I think you're missing the point of what he's saying. His overall argument is that DFS is more similar to casino blackjack than it is different.
If the whale negotiates the odds in his own games, he's changing the expected outcomes in his games versus the house, but he's not altering the odds for the honeymooners.
He might win physical dollars that were lost by the honeymooners, but because both players are playing the house, it's meaningless 'whose' money he's winning. He's taking money from the Casino's profit margin, really. They're gambling that he'll still lose more than he wins, and the slimmer margins will be made up in volume.
DFS is a skill game both in player selection, AND in skirting the rules, AND in getting the 'house' to tilt odds in your favor -- which directly tilt the odds even further away from the other players.
This is gambling. Not strictly defined as such, but if it looks like a duck, walks like a duck, and quacks like a duck, guess what?
Do you consider betting on horse racing as gambling? To be honest, for the professionals placing bets in this way, I don't (keep in mind it's very very easy to incorrectly place yourself in this category, and you will lose). But the vast majority of people betting on DFS do not, and can not, take this approach. For them, horse racing and DFS are very much gambling.