I would be suprised about the idea of fox scat scaring away brock, they can co-habit but i suspect only when the badger wants to, also i have seen latrines in large badger setts which are in collapsed entrances and still part of the network (probably unusual) but thats not quite the same to be fair. I have seen badgers marking entrances to rabbit burrows again hard to explain - although they can take rabits at some times of year so may have been marking a resource or just been spitefull to the bunny who probably got sticky paws coming out.
I think i would be tempted to have a widdle around the area in the evening to persuade foxy to not leave you to many more. Once they get a taste for the area it can be a bit iof a pain to get rid of them.