Hi Buggy Win,
Your friend is correct, but not for the reason they've given.* First I'd like to say that you need to let the foilage of the daffodils and tulips turn yellow before you remove it as the green foilage feeds the bulbs for next year's flowers.*
The main reason I don't recommend planting annuals over tulips and daffodils in pots is because the constant watering needed for the annuals will cause the bulbs to rot.* The native region for these bulbs is dry in summer while the bulbs are dormant.
I don't know where you live, but do be careful storing the pot over the winter.* You don't want freeze and thaw to cause your bulbs to rot.* If possible, sink the pot in the ground up to it's rim for the summer and winter.*
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.