One should distinguish the Paradise of our creation and the Paradise of our destination. In this verse, Jesus clearly speaks of the Paradise of our destination since that is where he ascended and what is His eternal home. Why did he use this verbiage? Possibly because He was speaking to a man not among His disciples, who never heard Christ's discourses of the Heavenly Kingdom and would not readily understand the term; while Paradise is something every Jew knew something about.
You have a theory that Jesus and the Good Thief went someplace else? Tell us more.
Wow, Catholics sure build on weak words. sigh