The problem of LTI is difficult because many BSEEs forget what it is after leaving class. So we have to be very grammatically careful to write clearly for even a technical audience. Memristors are linear when solving a circuit at one point in time, which is an important bit of linearity. Essentially LTI theory developed to describe what Fourier/Laplace transforms and LCR circuits and can do. So it's surprising to an EE that a fundamental passive element would not work in that theory. But it's not important to a non EE. So we have to phrase it such that a non EE will gloss over and an EE stops and says, "what does that mean again?" Because as you can see on this talk page, a lot of people are getting confused on this particular point.