100% right. When I said MIN or MAX functioned as SELECTEDVALUE(), I was envisioning the context being daily, where min and max would be equal. But you are completely correct that when you shift the context to monthly, these functions operate exactly as you anticipate (see table below where for the Var Value measures I just returned the value of the CurrentDate variable in each measure).
In this case, you will need to make a determination as you’ve done as to which function min or max is more appropriate to the analysis you want to do.
I hope this is useful confirmation, but you now seem to have a very clear understanding of how this DAX code is working.
– Brian