I sympathise.That seems to me to be unreasonable. How can one develop the skills of people about whom one knows nothing?. If they are really new to English, they have no skills in any case.
I think in those circumstances, if I didn't tell the people concerned what they could do with their job, I'd fall back on a 'find someone who... ' or 'ask your neighbour if s/he ..."type of task. This can serve as a very quick diagnostic test and give some, albeit limited, opportunity for feedback and remedial work.