While I am a volunteer and can't speak for the Museum or the Association, I would offer a few comments:

Fred Krock's description of the track situation fits with my understanding.

It is important to remember that the Western Railway Museum is the principal project of the Bay Area Electric Railroad Association. The Museum does not preserve and interpret all railroads, but preserves and interprets electric railroads of the west as is befitting an electric railroad association. There are other museums in the Bay Area (e.g., PLA, CSRM) that focus on preserving and interpreting steam (non-electric) railroads. We each have our role. We are an electric railroad museum, not a tourist railroad. We have an operating railroad so that we can provide the public with the experience of the electric interurban and street railroad in as historically accurate a context as possible. We hope that this results in an increased public appreciation of the historic and current role the electric railroad. We aggressively maintain the operating railroad so that both our operating cars - some of which are a century old - and our riders can have a safe and comfortable experience.
Our collection does include two Western Pacific steam locomotives and several heavyweight cars. Our rationale for collecting these items was the inextricable link between the Western Pacific and the Sacramento Northern. Perhaps we should not have collected them, but we did. Moving them elsewhere would be extremely expensive and we insure their long-term preservation by displaying and storing them inside buildings designed to protect them from the elements.

Finally, the extension of operations from Birds Landing Road to Molina is dependent on two inputs: (1) money to buy ties, poles, overhead hardware and bridge timbers and (2) volunteer time to put all of those in place. We welcome donations of either sort.