You don't understand how a Kensington lock is intended to work. The point is not to keep a laptop from being taken by brute force. The intent is to require that enough damage be done to the laptop in the process that no one will want the unit. Grinding a gaping hole in the side greatly reduces any resale value of a laptop which is already not much to begin with. Used laptops aren't worth much and one with obvious case damage is nearly worthless.
That said, lab equipment is a different animal and is worth a large portion of its original value. A hole in the side might reduce it some, but there would still be plenty of value to make it worth stealing even if it requires doing some damage.