Truly it is sad, but everyone is entitled to their own opinions and such and they're free to express it, even though there will be a few people out there that would see otherwise. In My Opinion I didn't even know about the cute icon until now and I think it's a nice little change since YouTube usually changes / add things that associates to the occasions that could be happening around the world and it's probably out of respect.
But as long as we have helpful, supportive people out there, the community doesn't have to be so cruel or heartless because there's some good in it, if that makes sense. Times change and so do people's way of thinking because we're constantly evolving, while others remain the same and again, it's how they view things. It may not be the same reasoning or the way you may want to see it. But we also have to allow their right to speak out on what they feel about it.
We can try and tell them one thing but it'll be like talking to a brick wall and some are stubborn or just don't / aren't ready to accept and we have to at least consider / respect their opinions and move away from it because it could potential hurt / wound them.
It is quite depressing and sad. People always complain about how much this world is just falling apart what with all the wars and hate going on. But then they will go nuts over something like this just because they refuse to accept it. What a twisted world we live in...
I personally have not seen the video, so it's possible that it's not a well made video or a portion of the dislikes are for that reason and not homophobia. Also, people are more likely to have a negative thing to say about something they dislike than a positive thing about something they like. There are probably people actively adding their negativity in the comments because they feel obligated to, and are angry. Most people who actually like the video wont really say much. I also wouldn't be surprised if somebody linked the video to a large homophobic community to funnel hate. So, because of that, that ratio of likes to dislikes and negative comments to positive ones may may not reflect the yt community. Don't assume the whole community is hateful.
HOWEVER, while yes, these are just opinions being posted, is is SUPER disrespectful to say that somebody shouldn't care for WHATEVER reason that they are being posted. Yes, people are entitled to their own opinions. Yes, I understand I cannot change their opinions. Yes, opinions by themselves are not hurtful. But when people go out of their way to promote negative behavior and negative opinions, it is HURTFUL. People in the lgbt+ community are dying everyday due to homophobia, and I refuse to respect their opinions that people like myself deserve to die. These are not "innocent" opinions, it is hate speech that is ruining peoples lives. So no, I am not going to respect their opinions or ignore what they say. Sorry, just trying to put things into perspective.
Edit: Yeah, I understand that most of the comments are just 12 year olds, or fake accounts, or old people who aren't gonna kill anyone, etc. etc., but in the long run, homophobia is homophobia. People like this are still the people who will bully lgbt+ kids, parents who disrespect their lgbt+ children, people who will spit at or tear gay couples apart in public, and/or people protesting and voting against on equality laws. And even if not, they will support the people who do and validate them.