Obstruction question

[JPhanatic]

Batter hits gapper and is heading for an easy stand up double. The first baseman for some reason goes to the inside of the bag right in the path of the runner.
Runner stutter steps and makes contact with first baseman as he rounds bag and after being taken off stride by contact just rounds the bag and decides not to try and advance to second base.
Umpire had arm out indicating obstruction but did not award runner second base because he did not attempt to take second base.
Umpire told runner after play that he had to keep going, and if thrown out would have been ruled safe due to obstruction.
Is this the right call?