This creates two classes of users and significantly reduces the percentage of the money supply used to secure the network.
Why? Here we see no explanation but just a statement of "fact" (or in other words "bullshit").
Additionally both of these systems suffer from the potential that a large stake holder could perform a denial of service attack by refusing to include some or all transactions.
They seem to have overlooked the "penalty" for not forging here.
Not forging does not mean, not including certain transactions.