Now is a good time to sell random 4-5 L/N but isn't a good time to buy.
That Chinese company which bought 30.000 and made a lot of advertising to drive the price probably is selling them now in secret.
When it will be realised that they have no value to Chinese end users, the biggest domain bubble will crash.
That is actually very easy to check. All you need to do is look at the whois of domains registered on July 27th and see if any changes.
But I don't get your point.
1. What's wrong is they sell it, in secret or not in secret?
It's investment company, they bought domains to sell them and make profit.
Having 30K you can receive end-user requests every day and sell some domains for $500-1000.
2. How the fact that they sell it will influence the market?
I assume that they sell it to
a) end-users who not going to drop them
b) domain investors, who also won't drop them after spent good money on purchase.
This way risk of one company dropping 30K domains in one day is spread on many other owners and reduced significantly.
But as we stated before, market professional don't drop domains that retail for $150-200 now, and maybe go for $300-500, by next July, they can just resell small part on market and make enough money for renewal.