  The high-mass X-ray binary LS I +61{\deg}303 is also cataloged as a gamma-ray
binary as a result of frequent outbursts at TeV photon energies. The system has
released two soft-gamma flares in the past, suggesting a magnetar
interpretation for the compact primary. This inference has recently gained
significant traction following the discovery of transient radio pulses,
detected in some orbital phases from the system, as the measured rotation and
tentative spin-down rates imply a polar magnetic field strength of $B_p \gtrsim
10^{14}\,\mbox{G}$ if the star is decelerating via magnetic dipole braking. In
this paper, we scrutinize magnetic field estimates for the primary in LS I
+61{\deg}303 by analyzing the compatibility of available data with the system's
accretion dynamics, spin evolution, age limits, gamma-ray emissions, and radio
pulsar activation. We find that the neutron star's age and spin evolution are
theoretically difficult to reconcile unless a strong propeller torque is in
operation. This torque could be responsible for the bulk of even the maximum
allowed spin-down, potentially weakening the inferred magnetic field by more
than an order of magnitude.
