No, it's not Castlevania. It's a great game, but it's just not Castlevania.
And Mario Galaxy wasn't really a Mario game because it was so different from the original 2D Mario games.
Resident Evil 4, not a "real" RE. All RE must be designed to be able to be beaten within 3 hours, or it's not a real RE title.
Ninja Gaiden Black, not really an NG game.
Prince of Persia: Sand of Time, not really a PoP game, as the original PoP didn't have a time manipulation element.
And SotN, wtf is that crap? This is a Metroid game, not a Cv game. You might as well be fighting the Mother Brain at the end. Hell, the main character isn't even a Belmont. Who's dumb idea was that. How can you call SotN a Cv game when the main playable character doesn't even wield a whip?
Yada, yeada, yada.... I think you get the point. You're free to have your own opinion, just as we're free to disagree. I think stating cart-blanche that LoS is in no terms a Cv game in the slightest, is a tad bold. Perhaps it would be best to say that at most, it doesn't match what you consider to be a Cv title because of X, Y, and Z.
In the end I guess some people can enjoy something they love being reinvented, and others can only enjoy that thing if it remains relatively the same.
How about this, think of LoS as an Elseworlds event (like the DC comics). It's Castlevania in a different realm/dimension/universe. That's pretty much how I view it anyway.