You can't provide evidence that it is indeed the alt account. That is just your assumption because of your disappointment with the account that was caught.
If you can publish evidence that both are alts, maybe some of us will also consider his behavior inappropriate.
Maybe I can also believe your words, if hosemary replies in the thread within a few seconds or minutes after the thread is created. If I'm not mistaken, there was a case like that in the past on the Beginners & Help board