Can you score a hold point with a temporary unit?

Yes, you can score a hold point with a Temporary unit.

According to RiftJudge FAQ #8906, the Temporary keyword does not restrict a unit's ability to participate in game actions, such as holding a battlefield or scoring points. As long as the unit is on the board and meets the requirements to hold a battlefield during your Beginning Phase, it will contribute to holding that battlefield and earn you the point.

The unit is only removed from the board when the Temporary triggered ability resolves at the start of your Beginning Phase (Rule 816.1.b).