Joh Yes, it is a bondage device. Like handcuffs or leg shackles. If someone thinks a girl keeping her legs together is more important than her being able to walk, that screams wrong priorities to me.
Though to be fair, something similar could be said about restrictive thigh bands in general, but at least on those, a compromise between mobility and "behavioral enforcement" can be found/negotiated. A block piece is too far on the restrictive side of that balance to constitute an acceptable compromise for practical use.
