No. Sometimes people's colors are off, or don't go well together, etc etc. and a black & white version would be better.
But in this case the colors look great together, and I love how the colors of the c4d match near perfect with the colors of his clothes. But you can't tell that from looking at the b&w version. It looks boring.
I'm sure you made it in color first, and it looked great. Then you take out all the hues and get the grey leftovers. If you're going to make a black and white sig, then make it that way from the beginning, don't just snatch all the color off it at the very end.