Interesting indeed.
The e-brake is integrated into the rear caliper, so replacing it with a caliper without an e-brake appears legal per the rules. However, the actuating mechanism and cables cannot be legally removed since they are not integrated into the caliper. But which comes first? The implied "You cannot remove the parking break." (which means you can't remove the stock caliper). Or the "any metal caliper may be used." (which means, in effect, you can remove the e-brake system in part).
One of the great things about SM is the un-written "No Weenies Rule", which basically says that you'll be looked upon very negatively if you protest modification based on a slightly different interpretation of the rules that really has little effect on vehicle ability. If you don't want to rely on an un-written rule, you could write the SEB for clarification.
If it means anything, I wouldn't protest you.
