Lagerstroemia is safe. Assuming the plant has never been sprayed with Dormant Oil, Coppercide, fungicide or other petrochem, and is from a low-traffic smoot-free area.
The plant, if cut back hard in Summer, takes several years to grow back before it looks good again. If pruned back hard, even to near the ground, within 2 weeks of the shortest days of the year, then it regrows rapidly.
New stems can be trained to grow in a braided/macrame form, during HOT weather when they are somewhat more pliable, but they are generally brittle. These branches when twisted and contorted together, will fuse together over the years, giving the effect of a 'braided ficus' to a hardy non-tropical tree. Elm branches, and trunks of separate specimens can also be trained to fuse together to make a 'living fence'. These contorted branches fused together can add an interesting natural dynamic to terraria setups.