Eggs being kicked out of "Bristle nose Logs" seems to be a fairly common problem with Peppermints and Orange spots. PVC pipes are even worse for this problem.
Breeders who use these ceramic logs for common bristle nose don't seem to have any problems at all.
I use inverted terra cotta saucers for breeding common bristle nose, and, even though peppermints will take up residence in these caves they have never spawned in them.
I have "Logs" in a few of my bristle tanks but have never had a spawn in one of these logs...The fish seem to prefer the saucer caves or some impossibly small crevice or hole in a piece of wood. However, given that common B/N will spawn in some strange, apparently secure places, these logs are better than nothing.
At the moment I am experimenting with different 'cave' designs. Some male peppermints and Orange spots have adopted some of these experiments, others have attracted no interest at all.
To date there have been no successfull spawns, but here is hoping.
Alan.