Hmm, subjective opinion but I don't think ideas or concepts should be 'owned' or 'patented'...never agreed with that system, thank god its only temporary, imagine if heating your house, or cooling your car in the summer was only allowed if you bought a specific brand....I don't care much for outright copied 1:1 clones of a product at the exact price point of its counter part, but provided its at an extremely discounted or competitive price, or at least altered in a competitive manner which this 'clone' appears to be, I struggle finding reason to critique the individual(s) behind the product...
In fact, its not a 1:1 clone, its just the same form factor...if someone finds the most ideal way to do something, its silly we can patent such ideas and force others to license them from us for a term of 20 years prior to it being 'free' to use...if replicating form factors or simple air gun tech offends you, then...*shrugs*
-Matt