As long as he keeps to the rule that you need to have a 45 in one fixed week (Monday to Sunday) and a 24 in the next and doesn’t do more than 6 days in a row, he will be fine.
Additional rests are fine and do reset the 6 days. Say if you take a 45 and then work for a couple of days, you can take a 24 that wasn’t strictly necessary and then follow that with 6 days straight if you want. The 24 is still a weekly rest that can split periods of continuously working, it is just that you are using the 45 to satisfy the weekly rest rules.
I think your friend is clear to work the 6 days, but remember we haven’t seen his exact working schedule and are just going by what we understand from your post.