From what I know Willesden Green is not a stop for the Metropolitan line and isn’t shown on the map as being on the line. Instead it should only be on the Jubilee line.
There is historical infrastructure at Willesden Green for Met trains to stop there, but as far as I can see this last happened in 2005 for a few days at Christmas. CULG - Metropolitan Line
Okay understand that there is a potential that the station is part of the route. However as we can see it is hardly ever part of the route. As stations are given a status, then I would assume that it would be set as false when no trains are stopping at that station.