It would if this story and some others are cherry-picked THEN you have a clear decline toward evil. But with Threnody, his motiviations here are the complete opposite of what caused his decline in character later: Pride. Here, he's admitting he's not the smartest or most learned man regarding mutant genetics. Sinister is. That Threnody had the best chance at survival and for helping cure the Legacy Virus if she went with Sinister. It IS a grey decision.
Later on, during Extinction when he was desperately searching for a way for mutants to survive, he even joined forces with his evil self, Dark Beast. But when the latter almost murdered an innocent child, Hank beat the **** out of DB and realized he couldn't compromise his morals.
The long painful decline of his moral character occurred when he brought the O5 to the present. Starting from here, Hank became defined by pride and hubris. That no one else was capable of doing things the right way as he saw it. The next 7 years writers would write Hank in this way, other writers would pull him back and say he's been wrong as seen in that story I posted of him with Wonder Man. Then the next writer would drag Hank back to being a smug jerk. It made him look positively schizophrenic.
So, yes, if you cherry-pick stories in a vacuum, it looks like a steady decline into evil with no upsides.
Edit: I felt the need to clarify. I may be blinded by my love for Beast, but me and others see, instead of a steady, slow decline to evil, a pattern of erratic behavior from Hank starting in 2012 when he brought the O5 to the present. The character since then seems more like a prop being pulled in various directions by writers with their own wildly divergent ideas for Hank. This is what I meant by him seeming schizophrenic.
What I WILL NOT Believe, as I've heard some others say, is that starting in the 90's, there has been a great collaboration among all the writers since then to steadily write him to be evil culminating in Percy's run. Percy even implied Hank has been evil from the very beginning of his life, which makes it all the more odd that he brings back a supposedly 'untainted' Hank from his younger days.
What I will not