Definitely glue the block in.

And go with the nylon bolts. They'll save you in the long run.

And when using nylon bolts, get yourself a tap to match the bolt size. Then thread the wood block. Treat the hole with CA and when thoroughly dry, thread the holes in the wood again. You'll have done a couple of "better" things. You'll save yourself the time and money that T-bolts would have cost you. And you will be building a measurably lighter model.

And some day, when your models are living through the winter and you're getting them ready for the next season of flying..... Swap out the old nylon bolts. Nylon dries out and get a touch brittle. If you don't remember, don't sweat it.

And, oh yeah, please, when you're doing this nylon bolt retrofit........ take a minute to measure the nylon bolts and cut them suckers off so they don't reach so far into the airplane. Excess bolts sticking out look so tacky and well.... so sloppy. They're so easy to trim. Now, about those sloppy looking tiny little elevator/rudder horn bolts that're sticking through.......