How do you know they deleted their posts and got downgraded as opposed to them having the potential activity to be a senior member and that thus awarded them the merit...
If flash101k had not been a Senior member at the time of airdrop merit - he would not have received 250 Merit.
Looking at his profile BPIP is absolutely clear that the whole merit he received during airdrop (
https://bpip.org/profile.aspx?p=flash101k)
This is not an isolated case. Here, for example, the account which was Hero Member but then he deleted all his posts:
https://bitcointalk.org/index.php?action=profile;u=911155