Beardies can be picky so you'll have to try various things from the beautiful dragons food list before you find something he really likes. This is a fun part of getting to know your boy.
My guy hated mustard greens.
LOL!
I give mine Kale and dandelion greens together (from the supermarket). Also, (just my opinion) is to use caution with those mealworms. Not too many at once and not too often. Through research, I've read they
may cause an impaction risk, especially in younger beardies. Gauging by the pic, your beardie - though older, looks the size of a young beardie so for the meantime I would consider treating him like one till he gets stronger.
Initially, to get my boy into his salad, I alternated between mealworms and waxworms (waxies are considered beardie candy). I placed about 5 a day atop his salad like croutons, this helps bring him to the salad and hopefully he'll grab a bite of the leafy greens. It also allows you to monitor him safely regarding impaction (making sure he's pooping frequently). Another good idea is to try offering small pieces of fruit in the salad. My guy loves dark fruit like blackberries, blueberries and strawberries. He also enjoys pears, grapes and squash. Any kind of squash works, like butternut!
Now, my boy is 10 months old. Hes about 17 inches long from nose to tip of tail. My guy's daily salad consists of all the goodies I mentioned and he eats it throughout the day. I leave it in overnight so IF any crickets remain in the viv, they'll gutload on the remaining bits of salad and wont try nibbling on him.
Your guy really pretty small so I would stay away from superworms for now but Phoenix worms can be attained in varying sizes and though they appear similar to waxies they are an excellent food source.
Hope this helps. Good Luck.