For the grilled shrimp marinade: Toss the shrimp in a large bowl with the olive oil, garlic, oregano, red pepper flakes and sprinkle with salt and pepper. Let marinate in the fridge for an hour.
Preheat half of a grill to medium-high heat, or around 350 degrees F.
For the squash: Toss the squash with the olive oil and some salt and pepper and place in a disposable aluminum foil pan. Place the pan over the indirect side of the grill and cook, covered, stirring once, until the squash is just tender, but not browned, 8 to 10 minutes. Set aside to cool.
Grill the shrimp over direct heat until just cooked through, 2 to 3 minutes per side, flipping once.
For the lemon vinaigrette: Whisk together the lemon juice, honey, shallots and Dijon in a large bowl. While whisking continuously, slowly drizzle in the grapeseed oil, then the olive oil, until emulsified. Season with salt and pepper.
To assemble the salad: Toss together the squash, corn, snap peas, sunflower seeds, Aleppo, half of the vinaigrette and season with salt and pepper. Taste and check for seasoning, adding more vinaigrette as desired. The salad can be kept cold until ready to serve. Before serving, gently fold in the basil and cilantro. Then plate with the shrimp arranged on top.