No, doesn't make sense.
Anzac Day and Waitangi Day aren't getting tacked on to anything. They'll still be observed on April 25 and February 6, weekday or not, as they are now.
The big difference is New Zealanders will be newly entitled to a public holiday they receive most years anyway. In the interests of "a fair go" the two holidays should be transferable from weekends just as December 25 and 26 and January 1 and 2 are now.
It would be a lot more understandable if Brownlee's opposition was based on the $200 million cost - even though, as Labour leader David Shearer points out - given the low frequency it would occur (the next time is 2015) and the number of Kiwis it affected, the cost is just a few cents per worker.