You made two mistakes in your first sentence that case doubt on your entire thesis about ‘bad China.” ASEAN countries were never delusional about China, since they lived with the giant for hundreds and even thousands of years. All of them seek to balance Beijing and Washington so they gain maximum benefit from both countries, without offending either. Far from being delusional, ASEAN countries conducted good state craft.
Your history seems far fetch right there. the existence of one entity doesn't mean its the same from the past, it may carry the name and history but not its conscientiousness.
Empirical evidence show China’s reemergence has been relatively peaceful, when compared with rise of most of the other great powers. Far from being a revisionist power, China generally supports the current international order. China did not instigate current SCS troubles, as its actions were in response to changes to status quo by other claimants. In fact, until 2010, it did little build ups in the SCS, while other claimants reclaimed land, built airstrips, and established military bases.
China's reemergence is not relatively peaceful nor internally quiet. You are forgetting the leaps and revolutions they did. Also the support of international order is always ends in an agenda. As for SCS, all claimant parties are instigators and its just a matter of time one strong actor creates a new status quo.
Problem with your narrative is ASEAN and pre-ASEAN countries have been relying on the US for their security since WWII. They also looked to Washington for economic development for most of that period. But in the last decade, China displaced US as Asia’s economic hegemon. ASEAN will continue to lean of US for security, because Uncle Sugar is willing to provide. When that picture changes, ASEAN will look for a new sugar daddy for security. It may be China, Japan, India, or a group of nations in a ‘Concert of Asia.’
ASEAN countries are very cautious on an uncanny new power trying to dominate them. But because of the United States( they're not so bad ones you get to know them) has a positive reputation even as an adversary. Reputation is a important currency. When you term "Sugar daddy", you pretty much strip these countries as a sovereigns. One thing, China is not an economic hegemon of asia. if already has, economic embargo has to be demonstrated and a powerful tide able to pull the whole asia down, hence your empirical evidence is needed.