Pete Zahut - "The argument I'm getting is that their mission is to spread the 'good news' and obey god's commandments. For the good of the greater number, they disfelloswhip in order to thwart anyone who may be trying to undermine their efforts in accomplishing that purpose much the same way McDonalds might fire someone who was publicaly promoting vegetarianism or speaking out publically or to their coworkers about how bad McDonalds food is."
Sorry to be the one to say this, but there's a flaw in your premise, in that it assumes altruism is the primary motivating force in the WTS...
...which is a fundamental mistake.
To use your own comparison; McDonald's is a business first and foremost; it disciplines workers who act inappropriately - not because it wants to altruistically feed the masses (if that were the case, it would give people food for free) - but because McDonald's employees who act inappropriately negatively impact McDonald's financial bottom line, which, in turn, ultimately threatens its survival.
Now, I will acknowledge that altruism does exist at the boots-on-the-ground level (to varying degrees) amongst JWs, but make no mistake; the WTS is - like McDonald's - a corporation.
They don't disfellowship in order to "thwart anyone who may be trying to undermine their efforts" to "spread the 'good news' and obey God's commandments" (no offense).
They disfellowship - ultimately - to protect their bottom line and ensure the Org's survival.