I'm not sure what's not clear about the notion that large risk should be regulated. If a company is capable, due to size or what have you, of harming a large number of people due to malice or incompetence on the part of its corporate governance, then sanity demands it should be regulated.
However, small companies should be regulated as little as possible. I mean, assuming you want a working economy. I'm not sure you do - actually, I'm not sure what you want, but from the standpoint of pattern recognition of your strawman attacks, I'd assume you want to regulate all business as little as possible.
Where I suspect we differ is the degree of "possible".
In my opinion, any business that can destroy hundreds of miles of coastline for other people while still having a banner profit year? Yeah, that should probably be regulated, since the Invisible Hand ain't gonna do it. Look up the Tragedy of the Commons sometime; you might find it instructive. (Or perhaps not. It's hard to tell how honestly you're approaching this.)