This method doesn't allow use to see the future. It only reduces the delay in seeing (do to the speed of light.) The best we can do is to go the speed of light, then there's no delay (even tho the object maybe light years away. )

Does it mean past, present and future are illusion ?

So I guess since we don’t see distant galaxies changing shape if running with a telescope and alternating running toward and away from the said galaxy while looking through the telescope, it means that to confirm the teachings of this lesson, we’d have to have a way of examining the alien’s future chronicles (or auto-biography). We’d have to read that what it saw Earth doing while riding its bicycle toward Earth, is consistent with things in our park bench ancestor’s future yet in our (far future scholars) past.