Proof, if you please. Here's my argument:
Why is everything so different, then? If that move is canon, the design of every ship, including a major fleet vessel (TCS Tiger's Claw), is very different, outside the bounds of known Confed architecture. The Rapiers have problems as well, as they are new fighters, and the movie Rapiers are of a very different design. They also seem to be older. Even with Prophecy you can see traces of the older architechture.
I see nothing all that familiar about the movie Tiger's Claw. It looks more like an unholy combination of WC3 Confed and WC2 Kilrathi design philosophy to me. That Fralthi is also different. And that's a class of ship with the same name, not a vessel that has the (barely) plausible excuse of simply being a different ship of the same name. We know from Prophecy among other sources that the WC3 cruisers are the Fralthi II's, so there's something funny going on witht he numbering if that's also a Fralthi. As for that being a Confed designation being hung incorrectly on the ship, that is unlikely. Intelligence would give a new ship a different designator to avoid confusion until more information is available.
Angel is not the Wing Commander aboard the Tiger's Claw, Halcyon is. That's possibly a different usage of the term, so let's discard that particular fact, shall we? Angel is also a Space Forces Captain, not a Naval Lt. Commander, which is not only a different service, it's also a grade ahead of her rank in WC1. Paladin is still a pilot onboard the Tiger's Claw and will be until shortly before her destruction just after the end of SM2.
It's another interpratation of the same universe, I agree. But with the differences involved, it's hard to reconcile them into the same sequence of events. It seems to me to be more like the relation between main-line Star Trek and Star Fleet Battles: same source material, different interpratations.
Now, unless there is a fact buried somewhere I didn't find while checking the factual statements contained in this post, I am less convinced that is part of the universe, not more.