Their reaction here has been paired with new movement in the South China Sea, changed messaging through proxy Government (Oli in Nepal and Pakistan at large) and claims over new land that has never been claimed by them before.
Xi is using the fallout from Corona as a way to impose China on countries that are distracted by the pandemic as of this time.
> If this was an actual calculated move to take significant amounts of territory the big guns would be firing by now.
That isn't how China works. They are well know for their salami slicing (https://foreignpolicy.com/2012/08/03/salami-slicing-in-the-s...) approach to expansionism. Their current actions are perfectly in line with previous attempts at expanding borders and signaling intent for armed invasion.