I thought folks might appreciate hearing the end of this tale.
I did just as I said I would: beat a pint of cream till stiff, dosed it with Cointreau and 10x sugar, and folded it into the chocolate goo. This was about a 1:1 blend so it took down the chocolatey-ness quite a lot but improved the texture. I broke a couple amaretti over the top and served.
I put the rest away. The next day, there was firm mousse floating on top and chocolate soup underneath. This went on, day after day, no matter how much I took out each time! So, I don't think I was just eating into the mass of mousse: I think I had gotten the mixture to just the right consistency for gravity to be the deciding factor between solid and liquid. Very strange and I doubt I could do it again.
When all was said and done, I might have preferred the fudgsicles.