Why isn't Súaltam disabled by Macha's curse?

Question

In the Táin Bó Cúailnge, the men of Ulster are disabled by a curse placed upon them by Macha to feel her labor pains in their hour of greatest need, thus disabling them when the army of Connacht attacks.

Cúchulainn is immune to the curse. I've understood that he is immune because he is a beardless youth, and so not affected by a curse affecting the men of Ulster. It may also be due to his demi-godhood, as a son of Lugh, the Long Arm.

In either case, Súaltam, Cúchulainn's human father, is neither a youth, nor is he descended from the Tuatha Dé Danann.

The translation from L. Winifred Faraday states specifically that Súaltam was unaffected:

A warning was sent from Fergus to the Ulstermen here, for friendship. They were now in the weakness, except Cúchulainn and his father Sualtaim.

And this version combining the translation efforts of Joseph Dunn and Ernst Windisch has an apparently unaffected Súaltam out grazing his horse with Cúchulainn when the warning from Fergus arrives, and Súaltam sets out for Emain Macha (in 6: March of the Host). This is after the curse is first said to have taken affect in 4: The Foretelling.

Related question: Why isn't Loeg disabled by Macha's curse?

Answer 1

I wonder if it's because he and his "son" are in Co. Meath at the time. They were watching out for Medb's army at Iraird Cuilenn (Crossakiel, County Meath), not in Ulster.
Another explanation might be that after he sets out to warn the Ulstermen, first they don't heed him, then he accidentally dies, after which his head continues to warn them, and they finally get the message.
This might seem a bit meta, but if the storyteller and everyone else knew that he wasn't going to be in the fight, they wouldn't question his not being affected. (Since according to my theory as soon as he re-entered Ulster he should have been affected as well.)

Answer 2

I think Macha's curse was an ad-hoc explanation, and not a very well thought through one, for a story that had got out of hand.

The story probably started out much shorter. Ailill and Medb invade Ulster, Cú Chulainn holds them up by challenging them to single combat, and buys time for Conchobar to raise his army. The story then enters oral culture, and storytellers invent more and more combats for Cú Chulainn to fight. By the time anyone starts trying to put together a complete version of the story, there are so many combats that an explanation is needed for why it takes Conchobar so long to raise his army. A mysterious debility is invented, and the story of Macha's curse is invented to explain that.

However, there's one thing that gives it away. As soon as he discovers the invaders have crossed the border, Cú Chulainn sends his father, Sualtam, to Emain Macha to warn Conchobar. He doesn't arrive until after the whole series of single combats, months later. The story of Macha's curse doesn't explain that. The obvious conclusion is, the single combats didn't originally go on that long.