Consumable In-App Purchase and Restore Button

Consumables are not to be restored, just as you were reasoning in your original question.

From Apple's In-App Purchase Programming Guide

Consumable products, by their nature, aren’t synced or restored. Users understand that, for example, buying ten more bubbles on their iPhone doesn’t also give them ten more bubbles on their iPad. All other types of products are made available across all of the user’s devices. They’re also restored so users can continue to access their purchased content even after buying a new device. StoreKit handles the syncing and restoring process for auto-renewable subscriptions and for non-consumable products.