They should be much, much taller before the broccoli-like flowers appear. Gailan is a cut and come again plant, like broccoli raab, so you could try cutting them and hope they gain some size before the flower buds appear again. A with broccoli, you don't want them to open. My plants get over two feet tall before buds start to appear, and I think I cut them once for the stems and leaves before that.

Also, please understand that bolting is not the "end" of the plant. In your climate brassica plants can live and produce for years. 3 or 4 easily, probably more. It would be more accurate to describe it as the beginning of the process.

Leave some to keep on growing for seeds.