I know this is an older thread, but I thought I might update you guys on this issue. After mowing a full year with my SD last year, I decided I needed the shield before mowing season starts this year. Called Hustler direct again, and pretty much got the same response. Called dealer again, and apparently there have been a few more reports of this and even though he wasn't able to cover it under warranty, I was able to get it at dealer cost, about 33 bucks out the door.
I will be equally relieved to shield the hydros from the radiant heat and it will be nice not to have to park my mower in the driveway when taking a break. On a side note, there is a guy on ebay selling engine guards for 50 bucks or best offer, I picked mine up for 40 plus shipping. Plan on installing both when the muffler shield comes in.