I think I understand why.
Persia was invaded by the Allies, so it became 'Axis' and then surrendered.
Axis later counter invaded.
So the partisan is an anti-allied partisan, which is why it ignores the Axis infantry unit.
Once Persia has been fully liberated by Axis then the partisans stop appearing, so this is not a major issue.
However think it is a bug. Anti-allied partisans should not be appearing in Axis controlled hexes.

