I think we can reasonably argue that the statement is overdetermined. Charitably, perhaps the professor did mean mathematical maturity in the sense of "try lear

I think we can reasonably argue that the statement is overdetermined. Charitably, perhaps the professor did mean mathematical maturity in the sense of "try learning some background first, and give yourself the time to let your skills and intuition develop." Uncharitably, perhaps the professor did not, and meant mathematical maturity in the sense of, "you have an inherent deficiency that makes this an inappropriate undertaking for you." I think where the fruit of this discussion may be is deciding to what degree an authority figure like a professor has a responsibility or an obligation to their students and advisees to make themselves clear which way they intend their statements to be interpreted. Personally, this begets a discussion of the nuances between the obligations and responsibilities of communication between (1) strangers, (2) peers/colleagues, and (3) authority figures and their charges.