Why would I?
The cost of filing is fairly small, but to do it right, you need a patent attorney.
Super small market. In 3 years, I've only made enough money to make payments on the machine that makes them.
The "copy" in the picture would not stand as a patent infringement. But taking them to court would cost me plenty. And for what?
Lastly, I've been down this road before. In this case, the oval cut in the top of a piston is NOT new. The application appears to be, but I am not willing to cough up the math that makes it work to justify the application to the patent office.
In short, I'm flattered. Now if they would just get it right.