According to Wikipedia, it was actually after Disney took over. The first time the Emperor was referred to as "Sheev Palpatine" was the 2014 novel Tarkin, which does fall under the Disney Canon. The name was allegedly created by George Lucas, just never used in the EU, surprisingly.
It's been popping up on me at Wikipedia & co when I've looked him up during the last year or so. Every time I shouted at my computer: “No, not that Sheev guy, whoever that is, I want the Emperor”
This article from Tor links the name "Sheev" to the Hindu deity Shiva (regarded as "the destroyer" and "the transformer"), taking into account the use of Sanskrit for other Naboo character names: http://www.tor.com/2014/10/16/palpatine-first-name/ Kor
In The Phantom Menace when speaking to Padme he says "Let me be Frank..." Frank Palpatine. Straight from the bantha's mouth.
Why do you think he it plotting to take over the galaxy? No one will let him be Frank. Frank was taken already.