My argument is quite simple. There are people with experience that can help, and it can be beneficial to seek out those people, rather than fumble through things on your own.
That's not an argument that it is somehow unethical to issue shares without an underwriter -- which was the claim you appeared to be making originally.
If you're only claiming that there are people with experience who can help, that has nothing to do with conflicts of interest or ethical issues, and it's quite a bit less controversial.
As for whether it's better for an issuer to handle their own listing, "like AMC", that's akin to asking whether it's better to set up your corporate headquarters in Houston, Texas, "like Enron". Citing an example of poor corporate management and linking it to a particular geographical location carries no more logical weight than linking it to a listing decision.
As for exchange operators issuing securities on their own exchange, quite a few people seem happy with, say, The Nasdaq OMX Group, Inc., whereas quite a few people find it loopy when those running Bitcoin-denominated exchanges (or tightly associated with them) issue securities on those exchanges. The difference suggests there's something more at work in how people are viewing the two situations than the simple question of whether operators should issue securities on their own exchanges.
I suspect that the primary difference that matters on that particular question is people's awareness that ultimately, without identity, there can be no accountability. When someone wants to run an exchange but refuses to come clean about their own identity, people are right to be cautious, and people are right to want to enforce limits on what they can do, given their ultimately non-existent accountability.
There is a difference between genuine trustworthiness and simply not having screwed anyone over yet. The pseudonymity of Bitcoin-land makes it easy to be lulled into conflating the latter with the former, because we're routinely deprived of the kinds of additional information that would enable us to evaluate genuine trustworthiness and to distinguish it from its murkier proxy.
I think that people's caution about things like exchange operators listing securities on their own exchanges is a bit like a little alarm bell going off and reminding them about that fundamental lack of accountability and all the dangers that go along with it.