He could if he wanted to. He could lose 15 minutes on purpose the first day, and it would be clear to both press, spectators and rivals what his intentions would be. He could do some work for Alaphilippe and Jakobsen in some stages, and then go in breaks. In the off-chance that he would be able to outclimb Froome and Meintjes, he could even prove he can win the TDF. Because i have heard that that is all it takes to prove you can win the TDF.
But he could if he wanted to. I just don't think he would. There would always be this "what if" feeling and he does seem like the rider who would rather fail trying, than not even try.