#2 To maintain the element of surprise
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Since almost everybody was expecting Triple H to surface at some point during the main event, having him no-show the pay-per-view could have just been decided in the interest of maintaining a suspense factor in proceedings.
In today’s dynamic of a rampant IWC and quasi-kayfabe, the WWE not only struggles to deliver believable storylines and engaging characterization to the audience, but also to preserve the element of surprise in their product.
If one examines the situation along those lines, then not having Triple H appear at Clash of Champions makes complete sense, and could work in favour of the WWE in terms of adding a dash of unpredictability to the storyline that is developing.
Major rumor about recently released stars HERE