That USB key is listed with "512 MB or 1 GB DDR3 RAM". It seems to be meant for multiple USB "applications" so that's understandable, but it's not exactly minuscule. TinyGo does seem to run on other far more constrained platforms, which is impressive. But like I said, Go doesn't seem fundamentally different than Python when it comes to shoehorning it into embedded systems. Go doesn't seem capable of competing with C/C++/Rust where they really shine ("low-level"). The memory and performance profiles are significantly different. The TinyGo team recognizes the difference between Rust and Go (being two modern "systems languages") and suggests other benefits of Go that aren't efficiency/performance. To each their own, but there's a niche where almost all languages aren't suitable.
Like I said, I think the main issue here is terminology, but you brushed that aside. From a cursory glance, Xerox PARC definitely did low-level programming so I'm not sure what "the gatekeepers point of view" is supposed to mean.