  A thought experiment considered recently in the literature, in which it is
investigated whether a dyonic Kerr-Newman black hole can be destroyed by
overcharging or overspinning it past extremality by a massive complex scalar
test field, is revisited. Another derivation of the result that this is not
possible, i.e. the weak cosmic censorship is not violated in this thought
experiment, is given. The derivation is based on conservation laws, on a null
energy condition, and on specific properties of the metric and the
electromagnetic field of dyonic Kerr-Newman black holes. The metric is kept
fixed, whereas the dynamics of the electromagnetic field is taken into account.
A detailed knowledge of the solutions of the equations of motion is not needed.
The approximation in which the electromagnetic field is fixed is also
considered, and a derivation for this case is also given. In addition, an older
version of the thought experiment, in which a pointlike test particle is used,
is revisited. The same result, namely the non-violation of the cosmic
censorship, is rederived in a way which is simpler than in earlier works.
