This is a fascinating topic for a number of reasons.
* First of all, RARB is clearly not focused on only one style of a cappella, nor is its intended audience only one kind of listener. However it does come with a perspective that's well grounded in contemporary American idioms with strong roots in collegiate a cappella.
Of course, every reviewer has a perspective, although some reviewer's point of view is fairly broad (a major newspaper's movie reviewer, for instance) and as such a reader can assume a large overlap in experience and perspective.
But when it comes to a cappella, there isn't necessarily an easily assumed overlap, as various folks have a variety of experiences and perspectives(barbershoppers, doowoppers, world music buffs, gospel singers, etc). In some cases this can be the difference between classical music fans and alt-rock goths. It's the rare review that'll address both perspectives seamlessly.
* Secondly, the barbershop is currently a rarified form. Why? Because over the decades SPEBSQSA/BHS has created a judging/coaching system that is so specific that it allows certain chords and disallows others, and this system is at the very core of the extremely centralized barbershop community.
To this end, if you're a "barbershopper" you know more than just the basics (melody is in the second tenor/"lead" line, songs will be oldies...) - you really understand the role of seventh chords, circle of fifths progressions, acceptable vocal textures and such, at least sonically if not theoretically.
This is almost unprescedented in artistic endeavors, as most art constantly strains to break out of boundaries, and I can't think of a form that's so completely organized by a central body. It's really more like competitive figure scating than rock and roll in this regard.
I'm not saying this is a good or a bad thing. It's just something to keep in mind, because a reviewer is either a barbershopper or not a barbershopper, and there's going to be a pretty dramatic difference in perspective between the two.
* To this end, I think it's important for RARB reviewers to "know that they don't know" - and not make statements to the proximity of contest-accepted barbershop standards, for example. It's clear this review has a couple of those statements, which strike the experienced barbershop reader as an immediate red flag that there are errors. And that's not good: not good to have errors, and not good to have a segment of the community feel immediately distanced when reading a review that's clearly in error.
* However, I also think it's important that RARB reviewers be free to review any album the same way. Barbershop may have a tome of arranging rules (yes, there's actuallly a 450 page manual), but that doesn't matter a bit to the rest of the world, and I think an album review is more valuable if it addresses a recording from a non-barbershop perspective.
* I think it could be very valuable for BHS to have an album reviewing service (if there isn't already one), although I'd personally urge the reviews to not rate quality by the same strict contest rules. Perhaps a third party is already doing this (I'm familiar with much of the barbershop world, but not an "insider").
* One last thought: I think it's valuable within the barbershop community for groups' pioneering to be recognized, but I don't know that there's much value to everyone else.
For instance, if an Armenian folk group whose music is based around triads steps out of the box and starts adding 7ths, it might be thoroughly important to the Armenian folk music community, but to the rest of us boneheads it's not all that important.
In this case, Realtime's album may be carving new territory, and this is much admired and appreciated (I'm reminded of the fantastic Gas House Gang albums last decade), but the fact is that the general a cappella community is so diverse and there's so much experimentation going on (harmony, texture, timbre, use of effects, etc) that a 13th chord in a barbershop chart isn't going to register on radar.
To summarize (if you're still reading this!), I think it's important for reviewers to not generalize about barbershop if they don't know, and also for barbershoppers to not expect kudos or credit for pushing boundaries within their form if it's not something a lay listener would notice.