Obstruction at 1st Base

[MONK]

We had an interesting play at 1st base in a 18U softball game. A ball was hit towards 1st base with alot of spin on it. The 1st baseman tripped while trying to field it and while rolling on the ground ended up lying completely across
1st base (covering both the base and the orange safety bae.) The runner slowed down not knowing what to do since the fielder was covering the bag.

Should this be considered obstruction (since the fielder did not leave any part of the base for the runner to touch) or since the 1st baseman was in the act of fielding the ball does she have the right to be on the base (or in this case covering the base)?