As much as I think family planning charities like MSI do good by preventing the pain of unwanted pregnancies on women, I do not think that we should factor in animal welfare concerns when it comes to family planning funding. The analysis assumes that an extra human will have the same impact on meat consumption as an average human, this isn't true. One extra meat consumer will raise the price of meat, reducing the amount that others eat, and meat production is far from perfectly elastic. One could argue there is some chance they might go on to work in the meat industry and raise supply that way, but at the current moment meat prices seem more dependent on available land then labor supply to me so that seems unlikely. Additionally, due to agglomeration effects an extra human may reduce the time until a full replacement of farmed animal meat with plant based or culture based meats. I do not think we should assume that bringing an extra human into the world should have a net negative impact on farmed animal welfare in expectation.

Considering impacts to non citizens abroad seems like a big deal and an obviously good idea that might end up drowned out in conversation by these other changes.

It's a very interesting study and a compelling idea. I think the big issue is that we need to look at the marginal impact of extra dollars on cancer research, this is looking at the average impact of money spent on cancer drug trials. Expected effectiveness of more money should be lower, as the most promising drugs are more likely to already have funding.