We present the results of high magnetic field experiments in pure 3He (in the absence of 4He coverage) in nematic aerogel. In this case the aerogel strands are covered with few atomic layers of solid paramagnetic 3He, which enables the spin-exchange mechanism for 3He quasiparticles scattering. Our earlier NMR experiments showed that in low fields, instead of the polar phase, the A phase is expected to emerge in nematic aerogel. We use a vibrating wire resonator with the sample of aerogel attached to it and measure temperature dependencies of resonance properties of the resonator at different magnetic fields. A superfluid transition temperature of 3He in aerogel, obtained from the experiments, increases nonlinearly in applied magnetic field. And this increase is suppressed compared with that for the bulk A1 phase, which we attribute to an influence of the magnetic scattering channel, previously considered theoretically for the case of 3He confined in isotropic silica aerogel. However, we observe the essential quantitative mismatch with theoretical expectations.