Earlier quoted context omitted.
Are you suggesting the only possible forms of anti-competitive coercion are government regulation or hit squads?
If it is voluntary it is not coercive. You can always not deal with your competition on unfair terms. In what circumstance could a 3rd party non-violent entity coerce you? The biggest one I can think of is "buying you out" but that is still either voluntary, in that the owners agree on the buyout, or it is a buyout of a publicly traded company, and I can't even get started on how non-free market the stock market is,…
Predatory pricing. Buying up necessary capital. Paying other companies to not deal with you (Suppliers, Retailers, Advertisers etc.)
All completely voluntary, and these are just off the top of my head.