Not sure if this is done intentionally by Bitmain or just by chance, most custom firmware will stop the electricity flow in the chips when there is no connection to the pool because it does save power, which makes sense right? no mining going on, the miner shouldn't be consuming that much energy, however, the custom firmware in that aspect could be worse, first, you don't want your miner to get too hot, then too cold and then too hot in case your connection is going through a rough time.
The second point is that if the weather is wet, and your miner isn't generating any heat, yet, the fans are still spinning, water will condense around the miner and it will be KaBOOM, so there isn't really a right or wrong way, both firmware custom and stock should give you an option as to what should happen when your miner isn't connected to the pool, and then depending on everybody's needs, they can choose what works for them.