It is up to you what you do with this cow. But I do agree, do not turn her out with the herd while hobbled. Give them a few days by themselves hobbled, then remove the hobbles and give them a few more days by themselves unhobbled. After that then turn them out with the herd. If she rejects the calf once they are with the herd, then for sure IMO there is only one place for her. And at that point I wouldn't worry about trying to get her to raise the calf. After all, you can't leave her hobbled for the summer.
Sure, in an ideal world it would be lovely if we never had to touch a cow or a calf. But reality is that once in a while, you ARE going to have to do something with one. IMO, this heifer is probably just a heifer, and they get confused sometimes. At least she wants to mother the calf. In our herd she'd get this one chance.
We had a heifer a couple years ago. She was the wildest of the lot that year. As it turned out DH had to help her, and he managed to assist her out in the big calving pen. So it wasn't much of a pull. Well, as soon as he got that calf out, she was up and gone. So he got the calf up to the barn, into a pen, and then set all the gates up so if he did actually get her up to the barn he could close the gates along the way (he was by himself calving that year). Turned out, he was lucky, got her up on the first try. She went up so fast though that by the time he got up behind her, she had made her circle in the barn and was heading back out. She spent the night in the barn with her calf, never licked him off or anything. So next morning her turned her out into the cull pen. So for a few days he was bottle feeding until we had a different cow lose a calf. Worked for a week or so on that, and it got to the point that when you were standing there, she would let this calf suck. So, we turned them into the back pen (where the culls and problem animals were). And continued to work on them. One day, when the calf was a week or so old, he looked into that pen, and what was going on amazed him. The heifer was standing their and letting her (rejected) calf suck. So we gave them a few days and then turned them out to pasture with the rest of the pairs. She never looked back. She will calve with her 4th calf this year and we have never had a problem with her since. She is still one of our wilder cows, but she has settled down. She was on the long list of culls, but we had enough drys that year that we gave her another chance.
OTOH, we had a heifer calf last year by herself. She loved every calf in the herd, would help mother all the newborns (after she had calved) We had fought with her for a couple weeks before that, she loved her calf, would mother it, lick it, moo at it, all that stuff. But there was no way she was actually going to let a calf suck. After a week or so in hobbles, we gave up on her. Sold the calf, then sold her...
So it is up to you what you do in the end, good luck with her.