I've been rewatching this segment of the show...my feelings about 1970 PT have changed somewhat, including the Jekyll/Hyde storyline. The more I watch these episodes, the more disgusted I get with Cyrus.
[spoiler] I mean, even as himself, he develops a strong attraction to Maggie, his best friend's wife. Does he have sense enough to stop drinking the potion? No, he doesn't. For a moment he does hesitate, but he all too quickly says the hell with it and takes the potion anyway so he can pursue Maggie, his best friend's wife, as Yaeger. Then, as Yaeger, he kidnaps Maggie, holds her against her will, forces her to write to Quentin that she's leaving him for good, then tries to kill her when she tried to escape.
With "friends" like Cyrus, Quentin and Maggie certainly didn't need any more enemies (although Angelique would certainly disagree).
I really find it hard to believe it never occured to Cyrus that as Yaeger he could do to Maggie what he did to Buffie...and worse. I think Cyrus just didn't care. [/spoiler]
Luciaphil hit it on the nail....Cyrus and Yaeger ultimately were cut from the same cloth.