The purpose was to insure that he could "make the tithe" in case he were ever unemployed.
At the same time my friend already knew enough about tithing to view that, in and of itself, as a sort of church based social insurance.
He didn't say, but I think he backed off that insurance policy, but as a "newbie" he was literally a sheep to be sheered by someone ~ so new recruits to the Mormons, or any other apostolic organization really ought to be very careful.
This stuff is not limited to the Mormons!