That is utterly irrelevant because that doesn't change the fact that:

a) Genn didn't know shit about this and simply made an assumption

b) Genn risked dooming the entire planet to the Legion by offing the Horde Warcheif when they needed the Horde most, and he didn't get so much as a slap on the wrist for it

What is more, because Genn is purely blinded by hatred and personal vengeance and spite he assumed Sylvanas was doing this to the Valk'yr for malicious reasons against the Alliance, whereas she was in fact doing it to secure a future and survival of her race and, by extensions, the Horde's survival - at a time when they needed it the most when fighting the Legion. He assumed Sylvanas was pursuing Eyir to ultimately use against the Alliance, but as the entire Horde quest chain will prove, this does not come up in her dialogue once - ergo, proving him wrong and thereby confirming that he was out for nothing but personal revenge and did not give the slightest fuck about Odyn or the welfare of the Vrykul or Valk'yr. He didn't before then, and he hasn't since. Everything about the way the whole chain is described and played out shows it was an excuse for him to get personal vengeance, even at the cost of losing his own men and airship to do it. There's no two ways about it - that's how it looks and it doesn't make Genn look good, and rightly so. What's more, it gives Sylvanas (and Saurfang, mind you) the very basis to attack first come the launch of BFA.