it's interesting to note that the earliest inscription for the "pied piper" uses the latin term magus, meaning magician - or, pagan. he's not called a merchant....and the idea of being sold into slavery takes a hit, due to the specificity of the term.

if they were led out of town by a "magus", that would suggest they were taken away by pagans, whatever the context.

that it was at the solstice would indeed reasonably be of some significance.