Buying silks is not a 100% guarantee solution to avoid getting ban. The proof is the poll in the thread I made about getting ban using Agbot.
How to avoid getting ban?
Maybe if you use the bot steadily. I
presume that JM looks into the overall statistics of a Char before banning it. If it seems that it's
unhuman then he get ban
Maybe thats why some unbotting people get banned by mistake. Their statistics could be way far than any normal human can do (24/7)