I would balk at accusing any charity of "asinine moral purity tests."

A charity explicitly prefers altruism over gain from moral conviction. One can hardly expect them to optimize for financial gain, even if there exists a compelling utilitarian argument that this would allow them to perform more altruism.

Indeed, this in my view is preferable - one need only gesture towards the infamy of "the ends justify the means" to make an argument against strict utilitarian behavior.