Answer

The requirement that one’s utensils rest on the Sabbath was not ruled as binding Jewish law, but there is an issue here of “do not place a stumbling block,” since you are helping him desecrate the Sabbath in a way that, without you, he would not have been able to do so (the case of “the two sides of the river”). Therefore, in principle, this is forbidden. However, if we are speaking about a secular person who does not recognize his halakhic obligation, then in my opinion the prohibition of “do not place a stumbling block” does not apply to him. Therefore, in my view, from a halakhic standpoint there is no prohibition here. But I personally would not agree, and if he has any tact he would not ask.