It is true that many box turtles, mine included, prefer to bury into soil or hide under moss/plants as opposed to using hides. However, if your baby already likes and uses his "cave" I would not remove it. Your boxie is very young, and at this age they hide a lot. As he gets some size to him and grows older he will be out and about more. I have always provided UVB for my boxies, but they have never spent hours basking under it. The main thing to remember with boxies is they like warmth, humidity, and low light levels. Even in nature, a baby box turtle is not going to be basking in the suns rays for hours.