Well I don't understand why, sativa strains are not like early harvest indica types, in stone, flavor or anything really.
Sativa strains produce a high unachievable with any early harvest Indica. May as well just put attributes where they belong instead of confusing the issue like you are, it's novel, but incorrect. A late harvest sativa strain is still racy and heady for the most part usually, energetic and uplifting. Similar to earlier harvest but more potent typically. An early harvest Indica is usually lighter in flavor and effect than one taken longer, but not always, and not any sativa component is found in an early harvest indica, it is just a different version of itself, not sativa.
I've grown marijuana since 1985ish, lots of experience with many strains, currently growing Tom Hill Haze (pure Sativa), and Bubba Kush (pure Indica). Hope this helps