Curiosity about how another life works is already the first step of living it.
Asking how a thing is done puts the mind to work collecting the method, and a mind holding the method rehearses it, and rehearsal hardens into practice long before anyone decides to convert. The prohibition falls on the question because the act downstream is already settled by then.
The snare is laid at the moment of victory, when people who have watched those nations fall feel furthest from imitating them. What the question costs is a slow drift in what feels normal to worship, with no single moment where a decision was made that could have been refused.