Tom didn't explain his second assertion, but it's important so I'm going to do it.
China is in the worst strategic position of any great power in history because it is critically dependent on resources it has to import, and it doesn't have control of the sea lanes over which it imports them.
China is neither food nor energy self-sufficient. It needs to import pork from the United States, grain from Africa, coal from Australia, and oil from the Middle East to keep its population fed and its factories running.
Naval blockades at about three critical chokepoints (Hormuz, Malacca, Sunda) would cripple the Chinese economy within months, possibly within weeks. China does not have the blue-water navy required to contrast control of those chokepoints. The moment any first-rate naval power or even a second-rate like India decides China needs to be stopped, it's pretty much game over.
As a completely separate issue thanks to the one-child policy, Chinese population probably peaked in 2006 and has been declining ever since. Every year in the foreseeable future they will have fewer military-age males than they do now. Most of those males are only sons; their deaths would wipe out entire family lines, giving the Chinese people an extremely low tolerance for war casualties.
Then there's the glass jaw. The Three Gorges Dam. Which is already in some peril even without a war - you can compare photographs over time and see that it's sagging. If anyone gets annoyed enough to pop that dam thing with a bunker-buster or a pony nuke, the resulting floods will kill millions and wipe out the strip of central China that is by far the country's most industrially and agriculturally productive region.
The Chinese haven't fought a war since 1971. They lost. Against Vietnam. The institutional knowledge that could potentially fit their army for doing anything more ambitious than suppressing regional warlordism does not exist.
I could go on. But I think I've made Tom's statements sufficiently understandable already.
Almost certainly not. Communist regimes invariably lie.
And we're not scared of China for at least two reasons. One is that China is demographically doomed. The other is that she is in the worst strategic position of any global power in history.