Arguably his two biggest characters in recent years are Person of Interest’s Harold Finch and Lost’s Ben Linus.
With that in mind, if he’s going to play a villain on Arrow, then it stands to reason that Linus is the clearer source of inspiration.
If someone as badass as John Locke had difficulty dealing with him, then it stands to reason that Oliver Queen may struggle as well.
We still don’t know much about who Michael Emerson is playing on Season 6 of Arrow at this point, but those remarks help paint a picture of what to expect.