The labor of a human being is not a commodity or article of commerce. No law against monopolies or combinations in restraint of trade shall be held or construed to forbid the existence and operation of natural gas marketing, labor, agricultural or horticultural organizations instituted for purposes of mutual help and not having capital stock or conducted for profit to the organization or to forbid or restrain individual members of such organizations from lawfully carrying out the objects thereof; nor shall such organizations or the members thereof be held or construed to be illegal combinations or conspiracies in restraint of trade under any law against monopolies or combinations in restraint of trade. No natural gas marketing organization exempted herein shall be organized in such a manner so as to control more than ten percent of the natural gas market. Nothing in this section shall be held or construed to justify any restraint of trade or restriction of competition except such as is incident to the protection and promotion of the interests of the members of such organizations, in view of their situation and circumstances, but such organizations and their objects and the effectuation thereof shall prima facie be presumed to be in reasonable restraint of trade or restriction of competition.