Not to the degree you’re insinuating, no. To prioritize custom builds over canon is to put MoCing first and foremost, to cater our ruleset around that community at the expense of the primary goal (or, at the very least, potentially at the expense depending on how much variation ends up existing). This is a canon contest that includes a MoCing component, and the primary argument thus far for allowing custom builds is that to forbid them would be to abandon all hope for creativity, which I simply don’t believe and have seen ample evidence to the contrary. As such, limiting the torso design strikes me more as a theming challenge for how to build creatively in spite of that than an outright restriction that is inherently a bad thing.
None of which will be regulated based on our rules. As I mentioned in my earlier post, we don’t plan to restrict anything aside from torso-usage, as the only canon stipulation placed upon the Hagah by Greg is “Metru-styled builds.” Although Norik and Iruini do share the things you mention, using other Toa teams as an example (such as the Mata), there exists enough precedent for variance to where system pieces, lower leg armor, flipped torsos, etc. could be totally fair game, as well as ample amounts of torso armor designs, limb armor designs (that could potentially be custom and multi-piece), etc.
Please remember that the Hagah are not illusory figures in the lore who were kept mysterious for the sake of their mystique (Tren Krom, Anonna, etc.). They’re not Titans like Artakha, these larger than life figures. They’re Toa. If the winds had blown differently or if LEGO had more of a budget, we could’ve gotten them as sets. LEGO could just as easily have made Bomonga or Pouks instead of Norik and Iruini. As such, from a purist perspective, keeping them “set accurate” (within reason and acceptable deviations) is certainly on the minds of many in terms of this contest. That is, in essence, the primary goal; creative MoCs and cool amazingly drawn artwork is a secondary goal.
And if that doesn’t jive with the MoCing community at large, there will be many other contests besides this one. 