You were correct. The clerk was mistaken.
I just leave them in the pot they're in when I buy them. Do remove the spent blooms, as that will allow the leaves to pour all of their energy into the bulbs, for next years flowers.
If you leave the spent flowers on, they will produce seeds, and your bulbs might not bloom the following year. The seeds may or may not be viable, but would require a few years ... 5 years, if my memory serves me correctly ... before they would produce blooming plants, if they even grow at all.
