The person breaking the law by streaming their Sky content has paid for it, so not stolen goods in my book.
You're reading the wrong book then.
They've paid a licence fee to be allowed to watch the feed under pretty limiting circumstances - including things like a single room (unless they pay the extra multi-room fee), and not being a pub, club, hotel, oil rig etc. Like most things governed by copyright, you only ever purchase a limited licence, to a restricted set of rights.
The licence fee doesn't give them the right to copy it (notwithstanding UK law grey on making a recording for own viewing purposes later, and the even greyer situation that Sky provide a box to store those grey recordings on), but certainly doesn't allow them to redistribute it.
The act of redistribution makes it illegal (or, at least, a broken contract), and in the analogy, it is the redistributed stream that becomes the stolen goods. In the same analogy, someone receiving the stream is handling stolen goods.
I assume you would not feel comfortable watching Sky in someone else's house that they had paid for.
Perfectly comfortable, in a legal sense - the licence fee they have paid covers those circumstances, making it fully legal.
It's the same old 'loss of revenue' waffle
Which you appear to counter by the same old 'isn't a loss of revenue' waffle.
Irrespective of what side of the fence you sit - whether you believe it to be justified behaviour or not - redistribution is illegal. The side of the fence you personally sit on will determine whether you feel justified in watching such a feed or not - but if you are going to tell others to watch the feed, isn't it right to let them know that there *is* a fence, and let them choose which side they want to be on?