Propane boiler in basement?

Well, my friend's Slantfin Lynx install is on hold. Seems the factory that makes the unit they ordered was in the Sandy zone and production is either still down or at least not back up full capacity. So his delivery ETA is unknown.

But I have a generic question about propane fired boilers and furnaces after glancing at the Lynx manual. There was a major warning up front about not installing such units in basements where, being heavier than air, any leaked LP could pool up and be an explosion risk. The warning cited the uniform mechanical code and mentioned that there were approved compensatory measures but didn't say what they were.

My friend spoke to the inspector before ordering (inspector did not visit yet) and he supposedly said it was OK to install these in basements.

So, what's the story with this? Is having a drafty old dirt floor basement good enough or will he have to work out a way to positively ventilate the low points of the basement below the unit and LP gas connections?