Hunter's Moon is no different, we get an insight into the prevailing mentalities of the two factions involved; from the wolf packs of the Vlka Fenryka to the changes of the Alpha Legion after they have sided with Horus.
In particular, I urge listeners to consider the following points:
Who is Alpharius? To Torbion (sp), he was under the impression that he had executed the primarch, only to be stunned at the reveal that it was certainly not Alpharius the primarch, even though Alpharius obviously possesses a superior combat prowess than two of the Space Wolves' very best champions.
Firstly, it is quite a significant assumption to claim the Space Wolves in question were some of the Legion's "very best champions", and it is entirely plausible that an Alpha Legion captain (assuming the role of Alpharius) could match the physical prowess of the Space Wolves in question. To add to that: not once did the Space Wolf question how (relatively) easily he managed to execute a Primarch... certainly a degree of arrogance on his behalf.
If this not the primarch, then who exactly is Alpharius?
'Alpharius' in Hunter's Moon
was just an Alpha Legionnaire who had assumed the role of Alpharius to dupe the Wolves. I would say it's as simple as that.
The armour. In Hunter's Moon, the Alpharius that descends from the titular ship is described as "ornately attired, bare headed, his scalp gleamed copper in the sun". Gav Thorpe takes great pains to describe the primarchs' obsessive detail to making their armour as ordinary as any other legionnaire in DELIVERANCE LOST. Rob Sanders describes a foreshadowing of the Alpha Legions' actions referring to 'other' armour (the implications of this are hard to determine at the moment). Everyone understands that the traitor legions have changed their armour after they sided with Horus, all for different reasons. The question to ask, is why do the Alpha Legion choose to change theirs?
I would strongly suggest that this wasn't intentional on the author's part and was simply another example of minor author inconsistency across the series. To be honest, the Alpha Legion's portrayals since Legion
have been quite inconsistent and in some cases quite poor (Thorpe's Deliverance Lost
springs to mind). I wouldn't read too much into the differing descriptions of the armour. Besides that, Its also not too hard to imagine that the Alpha Legionnaire who assumed the role of 'Alpharius' to dupe the Wolves adorned more ornate armour to better play the role of a Primarch. After all, the Wolves weren't to know that the real
Alpharius (most of the time) wore unadorned armour to better fit in with the remainder of his Legion. After all, adorning more ornate armour is hardly a complex deception.
Honestly, I think you're reading too much into it. In my opinion, this audio revealed nothing about the Alpha Legion we didn't already know or hadn't already inferred. It simply reiterated what we have known since 2008 when Legion
was released: that some Alpha Legionnaires assume the role of their Primarch on occasion.