You choose the Crystal remake option and yet you ask about that quest? =P
The Eusine-Suicune quest is a subplot that was added into Crystal and wasn't in GS, but is in HGSS as well. Personally I do feel that HGSS is actually more a Crystal remake than anything - besides having that that which is the biggest addition Crystal had by far, it has the extra radio show Crystal had, a Battle Tower (only in hgss it's the tower + rest of the frontier), the ExtremeSpeed Dratini and quiz for the 8th gym... the only things HGSS has that Crystal didn't was (bar differing obtainable Pokemon but they always differ and minor details like poliwag in an earlier pond by a very short walking distance when you can't even get the Old Rod doesn't cut it for me as a notable difference) is the Odd Egg, and some would say Krys too but hey there's a girl protagonist anyways and better not stir up that point anyways. -_- So it comes down to the Odd egg, which is a shame it isn't in IMO but a minor thing from Crystal that isn't in and shiny Pokemon are easier to get these days (plus you still get the Red Gyarados).
So I like things as they are now - I see no need for a Crystal-only version (I like being able to choose the Silver remake anyways, as Silver was my first game =P)
