I doubt Relentless or TMT did much in terms of strength-testing or R&D. Honestly I could draw up that exact design in a couple hours on Solidworks just given the front end of the truck to measure from. There is nothing secret going on, make it how everybody else has made bumpers for our trucks, use 3/16" or 1/4" plate, and know how to weld.
There are no cutouts that are the same on the front, they even changed the shackle mounts, the only similarity is where they placed the bend in the front sheet but that is necessary to follow the contour of the truck. I'd like to see the backsides, that is what separates good designs from bad.
I love Relentless's stuff, but who cares if there is one out there that looks similar? The only difference (on the outside) between C4 Fab's and Relentless' is C4's sticks out further, has a lightbar cutout, and a hoop. I think more people point fingers when a product is made out of the country that looks similar to an existing product made inside. Would it be as big of an issue if TMT's was made in the US by an existing offroad shop run by Toyota enthusiasts? Nope.