Maybe there is a problem with this part. One could not delete a thread but the content could be change. If it will be merited and later on the OP change its content like spam post then definitely the one who gave the merit will be reported for not following the protocol on giving merit. LOL. The merit for that post will be irrelevant because its credibility was being altered and this might confused and could be label as merit farming.
You think , you can frame anybody by changing the content later on and we will be not able to spot it? If a post changes after 10 (may be 15 minutes) after creations, a edited timestamp is also attached to that post.
I clearly see you created post at 4:21 pm but edited at 11:53 pm. If you are merited between this time frame, I will understand you changed the post after getting merit. Anyways I guess Mods can find the original copy too, if they require.