My sim that started this discussion, Jacob Kruthers, had only been charming for a few sim hours when this option first appeared. My other sims that have been charming for awhile, even one who has the cobra, do not have this option. This option never appeared for me until the new patch and Ambitions even though I have played WA since its release.
I have received this option so far only with this sim both in Twinbrook and in Egypt. He hasn't traveled anywhere else yet. He is Brave, Friendly, Athletic, Loves the Outdoors and a Computer Whiz. He is now an Adult who has been charming his snake for a few sim weeks and I still receive this option, but only for him. I tried it with two different new young adults and one different new adult and nada.
My problem now is that I have not been able to actually use this option - I choose the person to have the snake charmed into and nothing happens.
Bummer.