If homosexuals want to vote conservative they’re more than welcome to do so. That doesn’t mean they should be accommodated.
Log Cabin Republicans are certainly free to try and change the party platform, but I see no reason why the overwhelming majority of Republicans who support traditional marriage should compromise with a small minority who want to change it. If they don’t like the party platform, they will simply have to decide what is more important to them, their homosexuality or their conservatism.
BTW, Whitman’s views are probably more common in our leadership than the party rank and file. Our elected “representatives” generally play lip service to the party platform only long enough to get and stay in office.