Manganese telluride (MnTe) has recently emerged as a prototypical g-wave altermagnet, providing an ideal platform to investigate the non-equilibrium excitations of altermagnetic order. Here, we report simultaneous spatial mapping of the local equilibrium orientation of the Néel vector, ϕ_L(r), alongside the amplitude, Δϕ(r,t), and frequency, Ω(r), of photoexcited spin waves. Based on these measurements, we place a remarkably low upper bound of ≈ 60 μeV (0.7 K) on the spin-wave gap arising from intrinsic anisotropy. This exceptionally weak hexagonal anisotropy (K₆) renders the altermagnetic order highly susceptible to optical tuning, allowing coherent spin waves to be driven by a photoinduced enhancement of K₆. Above a threshold pump fluence, our spatial maps reveal that this photomodulation manifests as a six-fold symmetric sawtooth dependence of Δϕ on ϕ_L and a cycloid-like modulation of Ω. Ultimately, the near-isotropy of the Néel vector in MnTe enables optical and mechanical control over the orientation of spin-splitting in the electronic band structure, offering new pathways for altermagnetic spintronics.