I find it far more likely that DotD is a nod to Maiden's incredibly passionate Latin American fanbase than an album of the same name. Sounds way too close to DoD.The spin on the beer website is that Day of the Dead is to honour the Mexican festival of the Day of the Dead since Maiden are going to be in Mexico and South America.
The Day of the Dead festival takes place between 31st Oct and Nov 2. Which times in with the beer release.
However, Maiden play Mexico on 27th -30th of September, a month earlier and the tour finished on 15th of Oct more than 2 weeks earlier. How much Trooper is exported to South America, would it be enough to justify a new label?
I think this explanation from the brewery is a red herring and the beer is still related to the album. I think it being the album title is more likely than anything else associated with the album.