https://www.tumblr.com/cursed-sonic-opinions/819360226188869633/heteronormative-ships-are some of you people have no clue what you're talking about and it shows. if you don't know what "heteronormative" means, here is a crash course:
heteronormativity is, by definition, the societal belief that heterosexuality is the default, most normal sexuality and thus superior to all others. it is the belief that the only acceptable type of couple is one hypermasculine, dominant man in an exclusive relationship with a hyperfeminine, submissive woman (and that woman "belongs to" him, like property.) heteronormativity is the rotting, cancerous foundation upon which homophobia and transphobia are built, and it is EXTREMELY problematic.
in a vacuum, a ship fitting the "hypermasculine, dominant man in an exclusive relationship with a hyperfeminine, submissive woman" archetype is not inherently problematic. however, we do not live in a vacuum; we are products of a culture that is quite often violently homophobic and transphobic. even if we ourselves are queer, we all have a subconscious bias towards heteronormativity. that's why it's so important that we do the work of challenging ourselves, our instinctual responses to media we like, and thoughtfully examining our behaviors for that subconscious bias.
that bias, like any bias, can sometimes manifest in the kinds of ships people engage in. often times, people who aren't doing that work will force ships into fitting that archetype because it is the most familiar to them, or because they believe (either subconsciously or consciously) it's the best or most normal kind of ship.
this isn't a tendency unique to Shadamy shippers, but it does get noticed a lot more with Shadamy in particular, i think. personally, i have noticed that SOME (not all!) Shadamy shippers will sand down the edges of both characters to force them into the "broken bad boy/soft girl who fixes him" trope, which can be incredibly misogynistic. people have a right to be critical of these trends where they crop up, especially if the people doing it are showing bigotry or biases in other ways.
like any ship, it just depends on how it's handled. if it's done well, in a way respectful to both characters and mindful of bias, Shadamy can be very cute! i have lukewarm feelings about it personally, but i totally see the appeal. hell, i have many friends who adore the ship, and i'm always excited to see what they make for it.
when it comes to this kind of thing, it's important to try to remember this simple truth: criticism does not always mean something is inherently immoral or problematic. it just means the person being critical is hoping to spark constructive dialogue. often they're sharing their critiques because they feel it can be done better and want to contribute in some way.
obviously if someone is being nasty purely to start fights and hurt other people, they're in the wrong and probably worth blocking. that is radically different from people sharing their criticism or talking about what they don't like about a ship on a public forum. when you call it "bitching" and rudely tell them to shut up in a public space just because you don't agree, YOU are being the asshole.