If probation specifically says "while on probation" and you are no longer on probation you should be able to get your license without the Interlock device. I see no legal reason to deny you. However, DMV could very well dance you around until you either get the Interlock or retain an Attorney.

Interesting side note - in my area the Police did a demonstration of how the system works. THEY couldn't get the car started! I don't know if the system was too sensitive - or what the sensitivity was! - but it was, umm, an interesting demonstration.