It's mostly the danger of vets finding semen inside of your animal, reporting it to authorities, and you get locked up and your animal's taken away and euthanized in a shelter because nobody wants a dog that got fucked.

I wouldn't say nobody is going to get caught in their own homes. Shit happens, no matter how careful you are or think you're being. Maybe someone's roommate comes home early, or a window is more visible than they thought it was, or someone forgot the cable guy comes today, or a curtain rod falls at exactly the wrong moment. With horses there's even more risk as many people don't personally own the stable the horse lives in. Regardless, there are an infinite number of things that can go wrong and nobody is immune from just having plain old bad luck.

I'd also like to point out that something happening in private doesn't make it less likely to be sadistic. Sadistic acts are just as illegal now as they were before the law passed, people who were interested purely for sadistic reasons won't be any more discouraged now (ignoring any temporary effect of it being a hot topic). People who were into harmless sexual acts might actually be discouraged, especially if they fear their animals might be confiscated and/or killed. People performing sadistic acts are just as likely to get caught now as before and don't likely have the same concern for the animal facing consequences if they get caught.

Don't underestimate "kink factor."

Time has shown us repeatedly that making something illegal does not reduce its appeal. Laws like this also make mental health situations... different, and not in a good way. I speak from experience.

This might be an unpopular opinion, but I'm kinda okay with this. Those who perform in acts will do so in the safety of their own home. They are less likely to want to get into it for sadistic reasons, and moreso because they are actual zoophiles who genuinly love their animals.

There's so many ways you can get caught. There's certain things you can do to prevent it, but no one holds out forever.

Who's going to risk losing their loved ones by posting videos for profit - which is another ethical issue on it's own, exploitation - if they actually love their animals?

I'm with you on that it's risky and for that reason shouldn't be done, but how is making extra profit an issue?
I'd say it may even improve the animal's life, depending on how much money you have. More money, more things to buy, also more profit for the animal.

How is putting a recording camera in the room when you're having a fun time wrong?
You aren't having sex because you want money, you're just doing this to make the most out of it.
Going with the exact same logic, you shouldn't enjoy sex because that'd be exploitation. Apparently you can't make the most things out of it, then.

nobody is going to get caught in their own homes

You'd be sooo surprised, man.
I refuse to give an answer why, you'll realize some day.

there is no evidence

DNA.

One is not entirely safe just because they're having zoosex in their own home. Things can go wrong and bad luck can occur. If a veterinarian finds human semen in an animal, they might rat out the person to authorities.

Anti-zoo laws are wrong because they do nothing to prevent cruel treatment of animals (and they are not about preventing cruelty to animals) -- animal cruelty laws already exist in Nevada to deal with actual cruelty, thus a standalone law irrationally banning sex with animals (in and of itself) is unnecessary. Anti-zoo laws also discriminate against zoos by punishing them based on people's prejudiced "morals" -- and by singling them out categorically without regard to individual merit.

There are many other side-effects of anti-zoo laws which cause more harm than good -- for example, more stigma, zoos going further underground, zoos constantly in fear that they might be caught, fewer trips to the veterinarian (out of fear that they would be outed), and the ability of a vindictive ex-boyfriend/girlfriend to use blackmail on a zoo. Anti-zoo laws also unjustly give authorities the ability to seize one's animals (theft) and imprison a zoo just for being who they are.

So oppressive anti-zoo laws do not benefit society in any way; instead, they ruin lives and cause suffering. It is wrong for a law to ban sex with animals even with no evidence of actual cruelty.

This new law is unlikely to deter zoosadists, because zoosadism was already illegal prior to this new law. The new law will also not stop people from having sex with animals (zoos will be pushed further underground). But it will ruin the lives of anyone who is caught.