Few things in that article make any sense. Buffer regions? Who exactly is going to start a land invasion of China? And a land invasion through Tibet, the roof of the world?
There have been historical times when the US-- essentially strategically secure-- has had a front to fight with Canada (1812) or Mexico (1849). Most recently, the civil war in Mexico (1917) had a large number of US troops fighting along the border right before the start of the US entry in the First World War.
(the Germans realized this was the strategic weakness of the US, which prompted the Zimmerman telegram.)
In a similar way China can be dragged down by wars in Vietnam, Burma, Korea, or India / Himalayas. Will it lose? No. But like the US and Mexico, a war at your border can make projection of power infeasible.