That because it the greatest solution we have right now to keep these offenders from uh repeating there assault on the innocents of society
How about locking 'em up and throwing away the key?
The problem is that prisoners sexually assault/assault/murder other prisoners all the time. Sending someone to prison doesn’t prevent them from hurting others, it just limits who they can hurt.
And I abso-freaking-lutely guarantee you that if you chemically castrate sex offenders they are going to be more likely to angrily sexually assault anyone they can in prison or otherwise. Think they can't do so without a functioning dick? Use your imagination.
Also, a large number of so-called child molestation cases are like swatting flies with a sledgehammer. Usually involving a 14 or 15 year old girl having sex with someone in their late teens to early twenties, or sometimes a married guy in their 30s or 40s hit up on a cop sting with the cop pretending to be 15- never younger. Creepy and worthy of criminal prosecution? Sure. But is sexual contact with a woman just a year under the statutory age of consent, or even being lured in a sting by a cop claiming to be one, really make that other person a "child molester", let alone remotely needing chemical castration or life in prison as some here suggest? It's bad enough that in Most states the Adam Walsh Act basically mandates such people be registrants for around 25 years without any chance of early release.
I worked on several cases at the firm I worked at involving dudes who talked to undercover cops posing as minors on dating apps and the dudes would turn down the cop's advances, make it 100% clear that they aren't interested in meeting them, let alone sleeping with them, and they still get arrested because in some states, just having a conversation with a kid about sex can get you in real trouble.
A lot of these undercover stings are complete waste of law enforcement resources just for the sake of finding someone somewhere to convict. Obviously if you get someone who's enthusiastically "yes I would love to have sex with you, a 15 year old, let's meet in my creepy van, don't tell your parents" that's fair to go after, but there's no reason to continue these conversations after you get the first "sorry I'm not interested, you're too young for me."
(that being said, I can nitpick your post slightly - I did encounter one of these cases where the cop was posing as a 13 year old, so they do pose as younger than 15 sometimes)