I just think it's very wishful thinking to think he can play based on his performance in the second half of 2018 and 2019, as well as the clear downward trend in his OPS+ and WAR every season. He's not as bad as his worst year, but he's also likely not above replacement level. His saving grace was being a CF and being a good defender and he lost that. Could a newly focused, well-adjusted Odubel be a different player? I suppose that's the only X-factor, but it's a lot to hope for (both the performance and the assumption that he's a new man).
It's a question we never got answered due to the unusual year, but the main answer to why he's still here is that they simply aren't allowed to demote or release him for anything other than baseball reasons. They had a perfect opportunity to let him play last year, hidden at the alternate training site, with no media or (real) TV coverage, and still didn't take it. I still don't think they are even willing to let him play for the Iron Pigs. In theory if all of our CFs got hurt in the same month he'd get a look, but that wasn't even true last year, he was still behind Moniak and even Ronald Torreyes played there once (as did Harper), plus there was one other AAAA guy in Allentown.
Right now, the answer to their thinking has to do with the virus, and the unknowns for this season. Herrera was a burden on the Phillies' luxury tax threshold last year, but they wound up saving a lot of money on him in real cash. The same will be true this year even if it's just 10 or 20% instead of nearly 2/3. And the tax no longer matters.
To me it almost seems punitive, rather than being sensitive to domestic abuse or bad PR. He let the Phillies down, both on the field and off, and they're happy to let him languish while they pay him handsomely for it. The best thing for him would be a release, to give him a clean second chance elsewhere (though I'm still not sure he'd get one). He might finally get that on Opening Day.