They are very welcome to join us. There is a special "Questions & Answers" Board where they can post their questions or they can join us on any of the other boards.
The Forum is PG-13 (and we will enforce that) but keep in mind that when observing wildlife, bad things do happen and there will be questions/discussions about it afterward.
If you child is sensitive to the peregrines' well-being, it would be wise for a parent or adult to visit the Forum with them in case they have additional questions or concerns.