I think people are overrating Maroon a bit, possibly because of his personality.
Quality player, but probably a 2nd or 3rd liner at best. While it would suck to have Vegas pick him, the smartest play right now is to protect Davidson.
You pretty much have to protect Davidson. Quality defenceman are difficult to find (have a look at next year's UFA list), he's cheap, and young, and would have more of an impact on the team's results than a depth LW'er.
Maroon will be 29 at end of the season, and will have 1 year left on his contract when the expansion draft takes place. He will be an unrestricted free agent in 1 year:
1. Las Vegas may not want to pick a guy who is one year away from unrestricted free agency.
2. After the McDavid extension, the key for the Oilers will be getting overperforming and cheap contracts in the bottom six. Maroon will be (rightfully) seeking a long-term contract and this may be his last opportunity to get one and secure life for his family. The team and player objectives are are complete clash and would be difficult to accommodate. The Oilers can ill afford to pay fair market value and lucrative term once McDavid's extension kicks in.
They just can't.
I don't think it's a hard decision at all. Protect 4 forwards (RNH, Draisaitl, Eberle, Lucic), protect 4D (Larsson, Sekera, Klefbom, Davidson).