One thing is sure, if one person is speaking many insider things (even though they are just speculation), it is widely believed that he's getting some inside information from sources. Or he is being made to speak that way by forces that want him to do so.
When critic Kathi Mahesh started blasting Pawan Kalyan sometimes logically and sometimes with blind shots, people who are noticing the whole act started to believe that there is some person behind him. And this speculation started doing rounds quite differently as each set of people started believing in a different rumour.
Few Hardcore fans of Pawan Kalyan started to feel that Allu Arvind is the man behind Mahesh Kathi. They felt that Allu's are quite unhappy with Pawan's way of distancing from mega family and making some bitter comments on Arvind during the recent political tour. For that reason, these fans feel that Arvind is the one feeding Kathi with inputs. In reality, this may not be true, because, for just a few comments, love and affection between Allus and Pawan(Mega Family) won't wither away. After all, that is decades of relation built on some 'mega' bonding and principles.
And then, the ones who believe that Pawan Kalyan's political entry is for the good and his arrival is not making rivals happy started believing that YSR Congress party is behind Mahesh Kathi's rattling. They are of the thought that Jagan assured Kathi to give a seat in 2019 general election and YSRC leader Ambati Rambabu is providing needed 'think tank' support to him. This also may not be true because if tomorrow Kathi enters YSRC, then oppositions will use this as their prime weapon to target Jagan, saying that the 'fan' feared Pawan and resorted to dirty attacking. Also, when YSRC himself has some loud mouths like Roja and Ambati, why do they need Kathi to target Pawan?
However, some people believe that Kathi himself saw an opportunity to venture into politics after his good friends advised him to target Pawan Kalyan to get more attention. They feel that Kathi developed political ambition after getting shot to fame with Big Boss and since then he started using Dalit Card much more to get popularity. Now by targeting Pawan, he got such a fame that an honest cadre who worked for years with a political party won't get.
So, if the question is who is that man behind Kathi, then the only possible answer is 'himself'.