broccoli, cauliflower, artichoke, to each his own...
Sure, let them eat what they want. What's the harm if you don't see any flowers before they are eaten?
Keep a steady supply of fertilizer coming and the plant will keep making flowers.
OT: It would be interesting to know if they have any taste or color preferences. this would be hard to delineate. It would take a well-designed experiment and a large number of plants in a very large environment.
Perhaps irrelevant: I find the dark red flowered hibiscus too strong in flavor. The same with hibiscus tea, to me. Yellow and orange flowers are milder in flavor, and are nice in a mixed salad.
And if you haven't tried the flowers of the related genus _Abultilon_, you should; delicious.