I'd say, it's a god-awful price, and influenced by United's fan base more than reality.
Bar weird circumstances, you'd realistically expect United to need to win the remaining three matches. That should be a 20-25% chance of happening, if the prices in the market for the next two round are anywhere near correct.
You'd then, to have value, need to believe that there's about a two-thirds chance of two out of the three teams above dropping enough points, ie. Spurs getting max 2 points, Arsenal getting max 6 points, and/or Chelsea getting a max of 5 points from the last two (or United catching up on goal dif). That's imho nearer a 30-40% chance than the 60-70% you're needing.
