Got rust on chain and cassette
Note to readers -  Squirt is a wax based dry lube, the chain was not hot waxed.

The rust is cosmetic. Its been caused because you stripped the protective coatings with the degreaser and did not cover the chain and cassette completely in a protective layer.  Did you dry the chain before applying the lube and did you drown the chain then wipe off excess? 

Did you reapply lube over the 7 days? A dry lube won't last that long. 

For De greasers I use a citrus based cleaner or specific bike 'chain cleaner as these are not as harsh as many of the automotive ones. They clean the chain without stripping it bare of protection.

Dry lube is great, in dry conditions and OK in damp conditions but you need to reapply it regularly and use the right amount (which is heaps, drown the chain then wipe dry).  Wet lube offers better protection in wet conditions. 

You can get plated chains if the rust bothers you.