I don't know, Stadiums are kind of like gold around here. They are very, very hard to build, and take ~ 10 years to get done. RB's stadium is in a decent area that should get better as buildings get built around it, PATH improves, etc. All of the facility dynamics are on the upswing. You could even see people moving back into Harrison from deeper suburbs if the NJTransit issues get worse with the tunnels, just to use the PATH, raising property values.
I think RB looks at this and says "if I can get X back, fine, I'll take it. Otherwise, I'm in on the cheap as far as operating costs go now, I've got a stadium I can use for friendlies & stuff, plus my asset is appreciating all of the time. Might as well sit it out another few years, wait until MLS caps the teams at 28 or something, and then sell to someone looking to get into the league when a $ 100m expansion fee isn't an option- thereby requiring them to pay more.
I don't think RB is here long term, but I think they are here near term, next 3-5 years at least. (I'd love to be wrong on that, btw). I think they see franchise values going up, and they know that they can lose $ 10m/yr on operating costs, gain $ 15m/yr on franchise value and still have players for Leipzig (or cash) down the line. What's not to love? Negative PR doesn't ruffle their feathers.