I guess we have to give the President his point on horses, without necessarily conceding its relevance to naval strategy. (There are other ways, beside horseback, to travel at speed on land. Ships are the only means for travelling at speed over the surface of oceans.)
Bayonets I'm not so sure about. A bayonet looks like a handy thing to have on your firearm in certain battlefield circumstances. As a different Corporal Jones was wont to say, there's nothing like cold steel for dealing with recalcitrant foreigners. "They don't like it up 'em."
Radio Free New Jersey comes up with this, ah, pointed observation.
If a bayonet is such an arcane and useless implement of war, then why do I have to file the bayonet lug off my AR15 to keep it from being an 'assault weapon'? Add one more item to the nearly endless list of liberal contradictions.