Besides lottery sites being easily made via either hiring a developer or purchasing one of the many copies of code which have been circulating for years now do you really think implementing a miner for monero is the best thing to do for the business? It might be in the TOS but, did you not want to mention that here?
Alright, go and hire a developer for 0.5 BTC for developing a site which is almost two years active with many daily users.
The Monero miner is not secret. User `akamit` has soon mentioned in the topic if you read.