What do you mean by "having to"? This seems to imply an obligation to be altruistic. Where does that come from? And how do you reconcile that with the service being voluntary? You seem to be contradicting yourself. No one is forcing you to be good.
More importantly, they framed the discussion in the following way (emphasis added):
If I sit on my hands, others will label me some other alignment, tarnishing my reputation. To be the perceived best neighbor, I have to enter into voluntary slavery.
In other words, the alleged problem is not that there is some kind of entity actually using coercion on anyone else, despite that being actually required for something to be
slavery. The problem is that sitting on one's hands fails to result in being "the perceived best neighbor." What lall wants is a world where sitting on your hands
persuades others that you are in fact the best of neighbors, or at least the best type of neighbor.
And, frankly? That's bunk. People are not going to give
anyone a reputation of "being the best neighbor" for doing
diddly-squat. You earn a reputation through positive acts, not an absence of negative acts--and, more importantly, you do in fact have to
earn that reputation, not simply be
gifted such a reputation from others for nothing.
To expect others to simply go along with your definition of what is best--and, in the doing, to laud
you as the best--without any work or persuasion on your part IS coercive. Like, literally. You are expecting others to adopt your standards of behavior without actually convincing them of that standard, and without doing anything at all that would evince benefit from that standard for them. That sort of thing could only occur when someone coerces someone else.
Altruism is not slavery. Expecting altruism before you grant someone a reputation of being the best neighbor
is not slavery. The only way altruism becomes slavery is if you ruin it by actually engaging in coercion, just as others have said--using violence of some kind (including things like starvation or confinement) to actually force someone to do beneficial things for others against their own will.
If your only problem is that people won't think you're awesome unless you do altruistic things, you aren't being enslaved. You're
living in a society, where others get to decide what reputation you have. Get used to it.