As long as the earth-sun orbit stays close to 1 au, then ejecting the moon wouldn’t necessarily be world ending. There would probably be some aquatic life extinctions from the loss of tides, and some nocturnal species might be affected by the change in light levels.

The sun diameter is 1.4 million kilometers, and the earth-moon irital radius is 0.38 million kilometers. So trying stick the sun between the earth and moon at the current orbital radius just makes the sun 1% more massive.