Anything is possible, but is it good for the tree? In arboriculture, through-bolting is a common technique for attaching rope safety devices, but it is not comparable to the load on a tree house. Through-bolting is very well suited for attaching smaller loads by means of rope suspension. The threaded rod should have a diameter of at least 20 mm (take rust into account), on one side there is a large 5-7 cm washer, on the other side a ring nut to which the rope is attached. Here you can find more information and alternative fixing methods.