When I was three years old I had a sand pit in the back yard which I used to play in. Tenebrioid/Darkling (the family Mealworms are in) larvae used to turn up in it and I used to love playing with them. Very rarely, one would bite me and I'd get very confused, it was rare enough for me to generally expect them not to hurt me, so the bites would always leave me quite puzzled! What does that have to do with reptiles? Not much! Well, I suppose if wild reptiles are dealing with the nasty insects out there, captive reptiles should be able to deal with mealworms... so you'd think.
Mealworms (Tenebrio molitor) are quite an innocuous species... we need those nerds from SBS to test this one and shut everyone up! Thousands of American gecko keepers who all recommend mealworms as a staple diet don't seem to be enough! I personally think that worrying about mealworms eating their way out of your live reptiles is a bit like worrying about worms being in apples, because you might cough while you're eating one, causing the worm to be lodged in your sinus cavities, and if you just happen to have an open sore in your sinus cavity the worm might squirm into it and get to your brain, causing sudden death.
Hatchling lizards, particularly dragons are prone to dropping dead no matter what you do. It is particularly common for dragons to hatch out and not really thrive, slowly losing condition and becoming weak, it's then that people often force feed them and the force feeding kills them, regardless of what is fed. This is fairly common in hatchling snakes which are left too long before being force fed their first meals - a severely emaciated hatchling snake will quickly die after it is force fed, whether it is given a pinky, fish, mince meat, eat or even a mealworm! People have reptiles die after eating crickets, cockroaches, lettuce, nothing... but I'll recommend that you don't feed your reptiles mealworms, because that way you can't blame me when they happen to die of some unrelated cause soon after eating them!
For the record, I've been using mealworms to feed frogs and lizards for almost 20 years and I'm yet to have one cause a problem. If I happen to have a mealworm kill something now, I'll figure that it's probably going to be another 20 years before I have another problem with them and other insects couldn't be much safer than that anyway.
Mealworms are also yummy and nutritious, which is handy when you've bred too many and don't feel like making a trip to the shops.