Greer’s “friendly aliens” is an oversimplification of the issue.
Most researchers are convinced there are many species of aliens who have contacted individual humans throughout our history.
The categories range from:
—Overtly hostile—these are some of the Reptilians (the hostile ones are call Dracos) and other aliens they control or manipulate (which include many but not all the “greys”).
The abduction and medical experimentation of humans is generally hostile. These aliens treat us like we treat cattle—including as a food source at times.
—Secretly hostile but leave us alone if we leave them alone:
The “tall whites” discussed by Charles Hall and Ryan Musgrave-Evans fit this template. They have bases/dens here and do not venture out very often. They live in remote areas. However if they are approached and feel threatened they can get hostile. Hunters and dogs have been known to be injured or killed by these folks.
—Scientific curiosity/tourism/resource extraction/trade—this can be positive or negative or neutral depending on the exact circumstances. One example—landed craft can give off dangerous radiation—approaching or touching them has proven to be a bad idea—though no malice may be intended.
—Good aliens—include many of the “spiritual” beings who intervene in positive ways. Even in their case that may be at least partially out of self-interest.
I agree, But I believe over all the good ones are dominant over the others. But like you say, not just for our interests, their own are on the line too.