Sounds like a wonderful school. It is dangerous in principle for the school to limit its admissions to low-income students. Such a practice legitimizes discrimination in admissions, based on family income. This principle could easily be applied in reverse; a college might decide that it would only accept students from wealthy backgrounds. This is what the Ivy League did until about 50 years ago. Class warfare of this sort is a slippery slope. Discrimination based on social class, like discrimination based on race, is inherently unfair. Should sports teams have proportional representation based on race and class? Should businesses? Professions? Should we monitor the number of doctors who come from low-income backgrounds? Is there any room left in society for the concept of a level playing field?
Given that the school has been there for 150 years, operating on this model and very few people know it exists, I think we just might survive.