I have consulted my ATPL books (yes I am that bored!) and the Vmca is not affected by weight.
The ATPL books aren't the be all and end all of Vmc information, and in US certified/manufactured aircraft (which is a large majority), the aircraft is certified with the most unfavourable weight and C of G position so to say that weight doesn't affect is not true.
If you went into an interview quoting the ATPL book says I'm pretty sure how that interview is going to go....