I'm sorry that I can't go super in-depth on this, as I'd need to get acquainted with the source material again (I've been handling so much audio stuff lately), and really compare each mix in minute detail to say "that's okay, that's not okay", etc.
Let's just say this... there were a couple of tracks as "addition", like the room track of the harmonica, or Guitar 2 (which was an overdub for added flavor) and it's room recording being it's "double take" so to speak. If you managed with Automation and nudging the tracks, to get a more consistent mix out of it. That's fine. If the harmonica room track and guitar 2 was not part of the full mix, that's fine as well (it was stated that this is not mandatory). But completely dropping (muting) a part which was originally in the mix... then that's up to debate. Unless that was part of the rule set.
In this case, see MC26 (Oct 2016)
Mix Challenge 26 wrote:ADD-ON RULE: cutting away the beat section (in part or fully) during certain parts is allowed to create impact, as long as it's done moderately
Yes, it (muting) would improve the production/mix in some cased, if the client knows of what you're planning to (read: interaction with him), agrees to that, and if it's not cutting away important parts.
But imagine this: you have a pianist and two guitarists, and they make up the majority of the song. Each has their own part, their own story to tell via music. And you're like "nah, this part is too much - I need to cut it away to make room for others". While this might certainly help - it's changing the arrangement. At least in my opinion. Hence always the comment "you get the tracks 'as is' and you need to treat them like that". This will actually be important for the upcoming challenge - which is a dense cluster of various source signals.
Granted, this band might not have experience with recording - but definitely on stage. So going the Jason Newsted route might not always be the best route to go.
Ultimately, it's the decision by the song provider ("the client").
I can only nudge the participants into a certain direction to stick to the given rules. I only step in if somebody really stepped over the boarders.
Other than that:
I can definitely confirm that the mix is really a bit loud... maybe the "artistically treated summing bus" was a bit pushed too hard?
