Preheat the grill to approximately 400°F, setting it up for both direct and indirect cooking.
In a grill-safe pot, combine the yellow mustard, Dijon mustard, apple cider vinegar, molasses, honey, butter, Worcestershire sauce, garlic powder, black pepper, onion powder, cayenne pepper, oregano, and seasoned salt.
Stir until well combined, then place the pot on the grill over indirect heat and allow the sauce to warm while preparing the chicken.
Season the chicken thighs generously on both sides with the barbecue seasoning.
Allow the seasoning to sweat into the chicken for approximately 5 minutes.
Place the chicken thighs over direct heat and grill for 4-6 minutes per side, or until the internal temperature reaches approximately 172°F.
Dip each thigh into the warm gold barbecue sauce, coating both sides.
Transfer the chicken to the indirect heat side of the grill and cook for an additional 5 minutes to allow the sauce to set.
Remove from the grill and serve with additional gold barbecue sauce, if desired.