I didn't have a problem with it. Thanos scheming and using the Elders personality profiles against them works just fine. It's not like the Elders are omniscient, and omnipotent. Heck, Hawkeye beat both the Collector and the Grandmaster by outthinking them. Its been done against them before and since, and I'm ok with it because of their very nature. Their own manic obsession with "fill in the blank" is both what made them immortal but also fallible. You saw Maestro do something similar in the recent Contest of Champions.