Well yeah, it loses to light tanks if you expect to frontally assault each other.
Stuart is fairly weak AI, stuart isn't even that cheap either. What, 70 fuel and 240 mp for a kinda crappy generalist light tank? Most people just tech M20, then get captain, then get mediums. Stuart has fallen out of the meta bro, no need to nerf it.
60~ is hardly a nerf, just a adjustment to again, make the usf player choose between fast stuart or get a pack howi and delay the stuart.