Don't see how that decreases his chances. To the contrary, if his work is as good as the buzz from Cannes suggests, it'll only contribute to the buzz and make people pay more attention to him. He might not be a deaf actor (like Marlee Matlin who won in 1987), or play a mute character (like Samantha Morton, nominated in 2000) or be acting in a silent movie (like Dujardin), but I still think his apparent ability to impressively pull off a 90-minute near-silent one-man act could only be an advantage. Plus he's a certified, widely beloved and respected Hollywood legend who hasn't won yet, I bet the Academy would jump at the chance to reward him. The only thing that's holding me back from thinking of him as the top contender at this point is that the movie is gonna be distributed by Roadside Attractions, who's had some success getting films nominated before (Winter's Bone, Margin Call), but who knows how well they'll sell All Is Lost. If Fox Searchlight, Focus or SPC was behind Redford, I'd go for him over Di Caprio right now.