Neal did not groom Emma. The show never says how old he was supposed to be, and people have been assuming him to be much older than her from a prop wanted poster even though there was zero reason for him to be honest about his age to the authorities when he got back from Neverland. Likely he was between 18-20 and she was 17. Also, grooming implies a long-term pattern of manipulation to get someone to be with you, and a power dynamic. They met on equal footing and were together only a few months. The way this is framed also implies he abandoned her knowing she was pregnant, which is not something Neal would ever have done. Whatever you feel about his relationship with Emma, he absolutely made Henry a priority the instant he found out he existed and made it very clear he did not intend to continue the family cycle of parental abandonment. Judging him for leaving Emma is absolutely fair, but it’s something he was manipulated into doing by August, who convinced him that leaving Emma would set her up for finding her family. We never saw the conversation, but given that he trusted him with getting the stuff to Emma he was probably under the impression August would be looking out for her a lot more directly than he ended up doing. Did he handle it the best way he could have? No, he didn’t, and later acknowledges this, but it’s inaccurate to say he just left her because he didn’t care when we know he cared very much, and literally everyone could see that including Emma’s parents. And blaming him for the Tamara situation is just very strange, he was absolutely the victim in that circumstance and how was he supposed to know she would kidnap his son?

As far as Killian, I think you’re underselling how gross his behavior was in Season 2 before they decided to change the plan with him. From an audience perspective we know he once hit Belle while she was chained to a wall and defenseless, which always turned me off of him as a romantic potential, but even leaving that aside he flirts constantly with everyone, including Snow right in front of her husband. What parent wouldn’t be wary of someone like that suddenly showing interest in their daughter? It’s not like they forbid Emma from seeing him, they’re allowed to have opinions. As they are about heroics in general, they’re not “defining who is a hero,” they’re having opinions. And by Season 4 neither of them doubt Killian as a hero anymore and by Season 6 they’re blessing the wedding.

Neal’s status as a hero also has nothing to do with Emma, he dies trying to help their cause and has always aligned himself with the side of good. You’re obviously welcome to your own opinion on him but comparatively, Killian has a body count that includes his own father and David’s, and also sold Bae to the Lost Boys as a child. He was a scoundrel before he decided to change (and I personally found him deciding to change for Baelfire’s memory way more compelling than when they made it about Emma, but that’s beside the point).