Demi Lovato's bisexuality is even faker than Miley, who at least stuck her finger in pussy once. Lovato, on the other hand, only came out after she dropped a silly little song about girls kissing girls, and there was a backlash on Twitter by SJWs and even some half-famous young lesbian singers, who said they were all tired of straight women dropping songs on this subject. The coming-out was a PR move on Lovato's part, to hold back the negativity. A few days or weeks later, paparazzi took some pictures of her holding the hand of a girl whom no one knows, but that was in a very public setting, Disney or some such place, so you can say for sure that Lovato wanted the pictures to be taken. And again a few days later she tried (and failed) to set a social media thirst trap -- not for a woman, but for Henry Cavill.
As for Miley, I don't believe, either, that she dated women only to dodge her fears of men. I think Miley just hooks up with women for the paparazzi - that became obvious when she divorced her Hemsworth.
Let's refresh what happened:
1 - She immediately got a woman, Brody Jenner's ex-fiancee, after news of her divorce came out. And by "immediately", I mean one-day. World media goes on a meltdown.
2 - But, clearly, the affair, if it was real at all, was just an immature attempt on Miley's part to send a message to the media and humiliate her husband -- "I'm rebounding, I'm already over him after ONE DAY" -- while posing as a feminist, as that "independent woman who needs no man". But Miley shot herself in the foot: the quickness of her move opened an opportunity for her husband's PR to cast her as a villain in the divorce and claim that she was cheating on Liam, which she denied (personally, I believe her).
3 - The fling with the girl, despite being so played out for the public, only lasted for something like 2 days. There was no there-there with the woman, it was just an act, which is why I don't believe she cheated on Liam, at least not with this girl.
4 - Very shortly after this "affair", she got herself a boyfriend with whom she's been for much longer now; she even went on to say, after getting with him, that girls shouldn't try to use women as a replacement for men, explaining she only did so because she didn't trust she could find herself a good man again.
As said, I don't buy this explanation - I don't think she was ever scared of being with men - but I'm not sure how genuine is her interest in women, either.
I've had this discussion here before; I know it's useless to debate this with an L Chatter, but the truth is easy to see if you're not invested in trying to convince yourself that all women are queer: Miley uses other women for shock-value. Maybe she's actually bi, but if so then at the very least we have to admit she just takes men more seriously.