Nothing has changed here compared to the initial information.
The tires, being summer tires are not designed to be driven under 40ºF. They won't be damaged...but traction is significantly lowered under 40 until they warm up, similar to any summer tire. So the early thing was a warning (probably for legal purposes) to just not drive the car at all. (I've driven from as cold as 33º...a little common sense and caution goes a long way)
This notice mirrors exactly what the early information said: DO NOT DRIVE, or preferably, don't even STORE these tires under 20º. The rubber (apparently) becomes brittle. If you do store it...just don't move it, they'll be fine as soon as they warm back up to ambient temperatures.
Thanks for sharing again, MS3DALE.
The ZL1 and 1LE are no-compromises cars. They were built to go stupid-fast, end of story. This special care is part of that deal. I've experienced these tires on the track, and in the cold/wet weather. They're phenominal in the first case, and "good/okay" in the second case (as long as you recognize what you're driving...and using PTM mode 1 helps a lot). I intend to buy another set in a heartbeat. Plus - OE tires will allow me to keep Performance Traction Management fully-functional...other tires may not do that.
I park the car in the winter, anyways, so I guess the storage issue isn't a huge deal for me. If you don't, though - I hope you purchased a set of Blizzaks...