The hypothesis under test. GUT phase transitions generically produce topological monopoles; naive Kibble estimates overproduce them by >14 orders of magnitude (the monopole problem), inflation dilutes them by an uncertain amount, so the surviving flux is essentially unconstrained by theory. Relevant to the main question as the monopole/catalysis analogue of the stable-black-hole disaster mechanism: it is the scenario for which “nature’s own experiment” bounds exist.