I don't know if that helps, but since this thread is reminding me of various problems, I had gotten used to forget or ignore, reconsidering the issue I now come up with a one letter explanation: Q
Two episodes prior to "Yesterday's Enterprise" Guinan assaulted Q with a fork causing him considerable pain and despite Q's good mood at the end of "Déjà Q" I can't help but wonder if omnipotent Q simply forgave Guinan her assault on him.
After all, it's Guinan who's facing the biggest challenge in "Yesterday's Enterprise", i.e. persuading Captain Picard that he has
to send the Enterprise-C back in time to restore the correct course of events.
And she probably is well aware that she's also struggling for her own existence: Since the timeline has also been changed back to the 23rd Century (!) and we see a powerful Klingon Empire where Praxis probably did not
explode (ST VI) it's doubtful that there would have ever been an Enterprise-B
coming to Guinan's rescue (ST VII).
While she may be aware that this is another of Q's doing, there is no point bringing it up to the Captain Picard of the alternate timeline who has never heard of or met a Q.
The whole business with Tasha is another thing that could hint this direction. Though Q put her in a "penalty box" in "Hide and Q" he quickly lifted this kind of punishment.
At the end of "Déjà Q" he left Data with a gift but not the others. Being aware of the crew's sympathies for Tasha (unless he had a crush for her himself), he may have been inclined to create a scenario where Tasha's death would at least have a meaning rather than her stupid freak accident death in "Skin of Evil".
Just my 0.02$