The outspoken billionaire arguably has an interest in freeing up bandwidth currently being used for P2P traffic. His 2929 Entertainment venture is working to implement a distribution plan that includes simultaneously releasing movies theatrically at the same time they're available in home video formats. No doubt he'd benefit from reduced P2P traffic as it would free up bandwidth that could be used to deliver quality hi-def content. However, rival content providers are testing P2P technology, most notably BitTorrent, for their own content delivery. Even the music industry is looking at the potential of a P2P distribution model. No doubt they're less than thrilled with his proposal.
That doesn't mean his arguments are without merit though. He points out that "P2P is probably the least efficient means of distributing content in the last mile." While this is certainly true, it may simply be a sign that P2P technology is in need of efficiency improvements. It's even possible that the impressive growth in the U.S. of internet providers like Verizon, whose networks are built from the ground up around broadband data transfer, and have bandwidth several times that offered by either cable or DSL internet connections.
Cuban is certainly correct in asserting that service providers need to assess their infrastructure, determine who's using it and for what kind of traffic, and divide costs fairly. However, it's not as simple to say P2P users should be penalized. Like any traffic, if transmitted at the right time it can make use of otherwise unutilized bandwith, and if shut down during peak usage hours don't have to be a problem for other users. If it becomes a widely adopted method for entertainment companies to distribute content it could arguably affect the majority of broadband internet subscribers.