1B historically crash in their mid 30's. In the last 50 years there have only been 8 1B from their age 32-37 seasons (a likely age range for Freemans next contract) to have over 20 WAR in that range. And even that is a suspect number because it includes players like George Brett who moved to 1B way late in their career. Most others benefits from being able to DH as well. Honestly the only player in that group who I would consider a true 1B and stayed their would be Mark Grace. But players who start out at 1B just aren't productive in their late 30's. I'd rather not pay Freeman mega bucks to be part of that trend.
To be fair, WAR doesn't properly value 1b defense imo. And this phenomena isn't confined to 1b either. According to that spreadsheet, among position players there's been less than 50 total players to have at least 20 WAR over that age span, regardless of position.