I've seen a lot of older tv shows, and you get used to some reaaallly tired tropes if watch enough of them for a long enough time. Amnesia, cheesy pychic storylines, etc. I usually think "oh no not one of these episodes" if one comes on. I had that same feeling but magnified 1000x times over at the end of HLA, actually blurting out "oh for FUCK'S SAKE". Time travel is the absolute fucking nadir of modern sci fi tropes. These days, and it's blindingly clear in HLA's case, it only exists to try to undo earlier writing. It's absolute fucking garbage and has no place in HL.
Also Robert Culp and Robert Guillaume are dead, the way their characters left the games gave Valve an absolutely perfect out in that respect. Don't talk to me about sound-alikes, HLA's Vance is not HL2 Vance. He barely acts, moves or sounds like what we were familiar with from the earlier games, and now we probably have to live with skinwalker Vance for another game.