Perhaps a room temperature water extraction left to sit for a few days would work better. You could cover the jar or what ever you are using and this would prevent loss of allylbenzenes and other volatiles.

While mysristicin and friends may have relatively high boiling points, they are still volatile. So simmering the nutmeg will cause a loss of yield.

This is another interesting thread, assuming that the results can be replicated by other people, because this would mean that the compounds that make nutmeg active in everyone are not only soluble in alcohol, but also soluble in water.

This would also make nutmeg a lot healthier, since it would allow you to avoid the compound trimyristin. This is a fat that makes up a large portion of the nutmeg nut that is soluble in alcohol. It has been found to be able to induce fatty liver disease in lab rats and it may be sedative.

Removing trimyristin might make nutmeg more psychedelic. There has also been some speculation that trimyristin may be what makes the myristicin in nutmeg universally active. This report might be evidence against this idea.