Hi Twista,
I don't always feel totally comfortable giving advice about pole moves here, since I'm not as experienced as some others on this site. However since this topic has gone several days without a reply, I felt inclined to share my experience with the Genie. I am not an expert at this move, nor do I have any formal training in pole dance or fitness, so this is only my experience. This isn't necessarily the only way to learn Genie, or even the best way, but it is a way, and it's how I conditioned myself for Genie.
First, it took me a little while to figure out that much of the instability I felt when releasing my hands was not from my thigh-grip, but rather it was core. For some reason, it seems that it is harder to hold straight through the abdomen in this pose than in the knee hold or other positions. I realised after several hand releases that my arm strength was not compensating for my lack of thigh-grip so much as it was compensating for core. But the knee hold could possibly be used as one exercise to help develop strength through the oblique to hold this pose. Likewise the Cupid (that's the one with one the lower foot/ankle on the pole, while the higher leg is hooked around the pole at the knee, I think. If I am in error, please do correct me, anyone!), or a side-facing flag (instead of facing the floor). You can do sidebends also, with one foot on the floor and the other hooked around the pole by the top of the foot or behind the knee. I personally do this just as a conditioning exercise.
As for the thighs themselves though this pose isn't easy still even if your core strength is mammoth. I push really hard with my arm before releasing to make sure the pole is deep in my knee pits, and squeeze really hard with the hamstring. Your legs will hurt while you are getting used to this. I find that if my legs are out kind of wide, it is a little easier to hold. Maximum straddle is good for learning, but if you get more comfortable in Genie later on, the wow-factor increases a little if your knees are closer together enabling you to get further from the pole. You won't push your hips as far forward as you do for a knee hold (though they still need to be forward, just not to the same degree), so you have the luxury of getting some extra leverage by pressing your lower thigh against the pole instead of relying exclusively on squeeze factor.
Practice this close to the floor so that you can put a little of your weight on your lower hand on the floor while building strength for this move, as long as that is necessary. Also, it will be easier to catch yourself if you start to slip a little. Make sure you are comfortable in a handsfree Genie close to the floor before trying it higher on the pole. A spot and crash pads are always a good idea if those are luxuries you have access to.
By the way, keep a towel nearby. If your kneepits are sweaty this can be a pretty dangerous move to practice, so be sure to take a moment to dry off a little bit if you're feeling moist before having another attempt.
I hope that these suggestions are helpful, and also, I hope that it was shared tastefully enough. I respect that this is someone else's studio space, and hope that I haven't crossed any boundaries inappropriately.
But once your hold is secure, this move can look very pretty, especially on spin mode. Doing swimming arms, or belly-dance style snake arms can look really cute in the Genie hold! I'll post a Genie demo (not tutorial) in a couple days, when I set my pole back up at home. I loaned it to a friend who has a pole enthusiasm for a couple days, just to help keep myself off of the bloody thing, and give my body some needed rest. Practice does make perfect, or close; but overpractice does something else entirely! Haha!
Good job on getting the Genie with hand, and good luck on getting it handsfree!