He's got himself into a bit of a difficult decision. Up until now previous Cas auctions for coins with extra BTC loaded don't get as much interest as Cas coins loaded with face value.
Say a normal 2012 series 2 sells for 1.2BTC, if it was loaded with extra BTC then the price would increase per the value of the BTC loaded. There would be no premium on the surplus BTC.
Now say your friend had loaded 4BTC on his coin (on top the the 1BTC face value) it would lower the amount of people interested in buying it as they have to shell out about 5.2BTC for it.
Now given the fact that the 5 BTC also contain about an extra $1500 worth of BCH, you could assume that the people interested would be significantly less.
In short, don't expect any special premium. Someone will buy it for face value (BTC+BCH combined) with a small premium (possibly less than the usual premium on a series 2 2012 Cas single) as fewer people would be in for it.
I do not see how the bcash coins add value to the Cas coin. If people actually bought them to redeem then yes, but it is really the opposite. I personally think over funded Cas coins hurt the value.