I usually ask to speak to the partner in charge and tell them it's not our job to train their interns and can you please have your underlings read the instructions so we don't have to bill the client for our time educating your employees.
Though I usually use nicer language.
Since you're client has not elected the look-back measurement method they are defaulted to the monthly measurement method (determine each employees' status as of the end of each calendar month).
Accordingly there is no applicable stability period to worry about and the employee on extended leave of absence is not "full-time" for penalty purposes for any month in which they work less than 130 hours.