Most political leaders share in the general scientific illiteracy of the public. Their decisions on scientific and technical issues, therefore, should be informed by the views of the scientists. Alas, the scientific community has been notoriously timid about letting its views be known on controversial issues. The prevailing view seems to be that nothing is to be gained, and much might be lost, by speaking out on the scientific merits of such projects. It's a seriously flawed argument.
Funding is limited.
In opposing politically motivated projects, scientists aren't looking for a transfusion, they're trying to stop the bleeding. But taking a position based on the temporary occupants of political office is short sighted and foolish. Nevertheless, these arguments have intimidated much of the scientific community. Not so the physicists. The statements of the Society are reviewed each year by the Panel on Public Affairs to see if they should be retained, reaffirmed or discarded.