Assessing the stability of Majorana qubits (MQs) is essential for topological quantum computing. We propose a simple diagnostic scheme in which a quantum dot (QD) tunnel-coupled to an MQ undergoes charge Rabi oscillations detectable by single-shot readout. For ideal, spatially separated Majorana zero modes, the two total-parity sectors are equivalent and exhibit identical Rabi frequencies. In realistic finite-size or inhomogeneous systems, residual Majorana hybridization and coupling of the nominally remote Majorana component to the QD break this equivalence, producing a parity-dependent frequency splitting. To leading order, the splitting is governed by a linear combination of the two parameters characterizing deviations from the ideal Majorana limit, thereby providing a quantitative probe of MQ stability. Because these couplings also enter the effective braiding theory as sources of dynamical-phase errors, the measured splitting provides a direct assessment of parameters relevant to the robustness of non-Abelian operations.It can be extracted either from parity-resolved oscillations or, when both sectors contribute, form a characteristic beating envelope that provides a complementary, self-referenced measurement. Our results establish parity-resolved Rabi dynamics and Rabi beating as experimentally accessible probes of Majorana-qubit stability.