SD is not flooding anything. They're not attacking the network, Bitcoin users want to use their services.
Of all business, they're likely the one that has mostly contributed to miners via transaction fees.
This is the Circe-like character of SD. It looks attractive but carries great dangers. I am still concerned that this type of transaction source can scale far faster than the Bitcoin network.
Miners have no interest in keeping a "monster block". And they can easily choose not to build on top of such block, unless it is N blocks deep already, what would likely get the monster block rejected by the network.
Consider
variance. One hallmark of any successful, complex system is low variance of important intrinsic parameters. The Earth's ecosystem depends upon low variance in climate: e.g. the difference in air pressure between a cyclone and anticyclone is not a large percentage of 1 atmosphere.
In the case of Bitcoin, a very small block followed by a very large one is an unhealthy sign. A cap will help keep the variance (standard of deviation) of block size lower. This must be helpful to all miners as they know what to expect and plan accordingly, making incremental changes, which are always safer. A cap helps ensure all miners are on the same page about what is considered an expected block or a oversized one.