I don't see any particular reason that a government would decide to regulate PoS/PoW hybrids different than PoW coins or PoS coins. In the end it is the same concept: the blockchain needs to be confirmed by multiple peers to ensure that transactions cannot be duplicated, faked, etc. so in exchange for adding and confirming transactions to the blockchain the miner receives a reward in the given coin. It really doesn't make a huge conceptual difference if the transaction was confirmed via PoS or PoW, the point is that the miner receives a reward for using their resources to keep the coin running and confirming the blockchain.
You can look at it many different ways. With proof of stake, you're basically encouraged to be a monopoly man and horde capital. There's a large, financial incentive, with little effort involved. You're rewarded for being a whale, in other words. With proof of work, well, just like it sounds, there's a bit of work actually involved in claiming your reward. You have electricity costs, IT issues, you may even have employees that you pay to help run your operation. Operating a business sound like "work" to me.
When it comes down to it, you might as well rename proof of stake to "proof of whale", so we can really get a clear picture of what we're dealing with.
Factor in that you're double rewarded for holding a hyper deflationary currency, plus the stake claim at the same time, and there's little reason to ever spend the money. Double rewarding for *not* spending anything isn't something you actually want in a currency. Like the guy said, stake coins are "high yield investment programs", and will never be used to buy anything.