Why can Cain V. from the UFC ?

Jesus, get it right. You can't just sling these kind of accusations without being sure of your target. Jeff Monson has a rather random-looking hodgepodge of anarchist/communist/anti-capitalist symbols on his body. That may point to a rather confused political outlook but he is certainly not a racist. You may be thinking of Melvin Costa, Toni Valtonen or Niko Puhakka, all of whom have very clear Nazi tattoos.

Now as for Velasquez, the reason is because "Brown Pride" does not contain the cultural baggage that, for instance, "White Pride" does. Pride in ones race, generally speaking, does not necessarily mean one hates, or wishes to discriminate against, another race. However, the phrase "White Pride" has been used by many groups who explicitly do wish to oppress other races, and this, together with the long history of racist actions by white people throughout the world, makes the phrase "White Pride" rather too culturally loaded to be safely used. This is similar to the fate of the swastika, which to many eastern religions is a holy symbol, but is now 'contaminated' by the Nazis and no longer acceptable for display in the Western world. "Brown Pride" does not hold the same connotations, hence Velasquez can safely wear it.

Jeff Monson tattoos are not racist, Monson has Anarchy symbol tattoos.

Anarchy is the "Absence of government; a state of lawlessness due to the absence or inefficiency of the supreme power; political disorder."

"Acting without waiting for instructions or official permission... The root of anarchism is the single impulse to do it yourself: everything else follows from this.

Nothing to do with racism