The magnetic interference comes from the magnet which is embedded in the flywheel. It is there to operate the magneto ignition system, it makes no difference whether it is two stroke or four stroke. Different manufacturers outboards cause more or less interference depending on the physical location of the flywheel relative to the tiller pilot fluxgate compass.
I have had experience of three different outboards in use with tiller pilots, a Mariner 4 caused no problems. Whereas a Yamaha 4 and Honda 5 produce significant interference.
Hope this helps.