Why would one do that?
Block hashes are random. So the only way a miner could guarantee the next block will be a superblock would be to throw away VALID blocks which result in the next block being normal.
Every block thrown away simply means less revenue for the miner. While they would publish more superblocks, it isn't because they found them faster, it was merely because they threw away valid blocks which don't lead to a superblock.
Yes, the intent of the Happy Miner is not to gather as many coins as possible, but instead to disrupt the monetary basis of the currency. Thus dropping valid low-reward blocks is a key part of the strategy.
BTW: superblocks are generally speaking pointless but I don't see there is no mechanism to profit from this. At best an attacker could use it to drive down the value of the coin.
Again, the intent is not to profit. The intent is to disrupt. It's not as blatant as a 51% attack, surely. But such a Happy Seeder attack could do more then just devalue the coin. If it was really effective it would clearly show to everyone that the chain is vulnerable and not to be trusted. That's how coins die.