The Special part says:"This rage power is available to wereboars, wereboar-kin and those who associate with these creatures."
This mean that a barbarian half-orc can't pick this rage power?
This is your wiggle room, but it really depends on the GM. Personally I might allow a half-orc barbarian if they wrote their character as being from a tribe of orcish wereboars, but only manifest minor lycanthropic traits. Probably pick up a gore attack.
A stricter reading would probably require wereboar or wereboar-kin skinwalker.