If the equipment in question doesn't require a neutral (like much HVAC equipment), then the neutral isn't floating, it just isn't used/terminated on either side. I'm assuming you guys pulled in 6/3 or 8/3 romex, both of which have a #10 ground. Personally, I would have tied down the neutral in the panel side, but it isn't a big deal, it's just an unused wire at that point.

Remember that with 240v, you have 240v of potential difference between the two opposing 120v phase legs, and the opposition of phases are what complete the circuit all the way back to the transformer.