As I said in my post, you can't stop people from compiling it at home. But, you also can't stop people from downloading the object code. Minecraft is frequently pirated and traded. There is no effective difference. In fact, people who are interested in obtaining Minecraft outside of legal channels are just going to pirate the object code anyway -- it's not very likely they'll want to download and compile the source and go through that pain when they could just download the pre-built versions.
There is no additional risk to revenue. Individuals who want to circumvent the licensing requirements do it with or without source. Companies who may misappropriate the code know better than to do so because they know they will be sued and immediately lose, so they will buy licenses from Mojang anyway. Seeing the "cool stuff" that can be done by Minecraft's engine, etc., that hobbyists put together with the code, may in fact convince people with money to license it more than just keeping it closed altogether.
There is no additional risk to revenue. Individuals who want to circumvent the licensing requirements do it with or without source. Companies who may misappropriate the code know better than to do so because they know they will be sued and immediately lose, so they will buy licenses from Mojang anyway. Seeing the "cool stuff" that can be done by Minecraft's engine, etc., that hobbyists put together with the code, may in fact convince people with money to license it more than just keeping it closed altogether.