This almost reads like an attempt at a reductio ad absurdum of worrying about animal welfare, like you are supposed to be a ridiculous hypocrite if you think factory farming is fucked yet are indifferent to the cumulative suffering caused to termites every time an exterminator sprays your house so it doesn't crumble.
Relying on the mean estimate, giving a dollar to the shrimp welfare project prevents, on average, as much pain as preventing 285 humans from painfully dying by freezing to death and suffocating. This would make three human deaths painless per penny, when otherwise the people would have slowly frozen and suffocated to death.
Dog, you've lost the plot.
FWIW a charity providing the means to stun shrimp before death by freezing as is the case here isn't indefensible, but the way it's framed as some sort of an ethical slam dunk even compared to say donating to refugee care just makes it too obvious you'd be giving money to people who are weird in a bad way.
wat