It's entirely possible that members of FR are not representative of average Republicans. They may be more conservative.
The larger factor likely is that many people who oppose the nomination didn't bother sending an email in reply stating that fact. You can't equate a failure to object with support. But, the low response rate does suggest that there isn't a large number truly outraged.
FReepers may be more conservative than the average Republican, but not 2770 times as conservative. The gap is far to wide to be explained like that. Maybe as a whole we're 50% more conservative than the average Republican.