What is says is

Does this mean we shouldn't purchase it through Amazon or another retailer? I would much rather purchase through Amazon but that quote makes it seem like I won't get the five days early access. I will get the explorer's pack though:

The first quote does not mention participating retailers, only elderscrollsonline.com

I wouldn't worry, check out Green Man Gaming. It shows the 5 day early access:

http://www.greenmangaming.com/s/ca/en/pc/games/mmos/elder-scrolls-online-imperial-edition/

I'm sure every place will give you a 5 day early access code it you pre-order the Imperial Edition.