I agree with this now, after my experience today. Joey pinged to move, I said no, saved and quit, went to settings and changed the date to one month earlier, loaded the game, immediately saved and quit, set date forward one month to current date, then loaded game again. (this is the short version of the grass regrowth trick, btw) Joey pinged to move again, I said no and went to check mail. Phoebe was gone; she left a letter saying goodbye. As many times as I have done the grass regrowth trick, no one has ever moved out before. "It isn't safe to assume." Not sad about Phoebe; I have her amiibo card. She will be moving back in on Thursday! Might take a bit because I erased all my patterns, but, c'est la vie!