I'm sorry, but this is a terrible response. Clearly this person's expertise is in web design, so why would you expect them to pick up an entirely new domain of

I'm sorry, but this is a terrible response. Clearly this person's expertise is in web design, so why would you expect them to pick up an entirely new domain of knowledge when they're already able and willing to contribute web-design now? Having somebody who has only just learnt how to code contributing to a massive codebase is in nobody's best interests. All this will do is increase the workload of the developers who have to review the potentially crap code and, on top of that, it removes a potential contributor from an area where they could contribute far more valuable resources in a domain in which they actually have experience. Suggesting that the op picks up an additional skill in their spare time is fine, but not at the expense of being able to contribute in an area where they already clearly have experience.