I've purchased IDA Pro for years for legitimate reversing work, but on the rare occasion that I need to do some more dodgy work for clients, where I don't want to reveal any identity (previously name, now license number) via the watermarks in the database, I will use a pirated version of the software.

My point is that it is not possible to know for sure if the user of a pirated software is indeed a pirate, as there are reasons of privacy to use these editions of the IDA (as well as the most common one of just not paying for it in the first place.)

As to the question of whether Bushmanov has used a pirated edition of IDA for his work, it's interesting to note that the distributed .idb files are in two different formats - as far as I can tell versions 5.2 and 5.5, but the license key is the same for both: A2-86E4-B9BB-D3. It's not one I recognise from any of the common pirated versions but I suppose only Ilfak could tell for sure.