All you've demonstrated is that you don't know much about what happened in Grenada.
First, the legal government of Grenada had just been overthrown in a pro-communist military coup. The elected Prime Minister was put under house arrest and then freed by his supporters. Soon afterwards government troops in trucks began to attack the Prime Ministers supports and murdered the Prime minister. The Governor General of Grenada as well as the association of Eastern Carribbean Nations asked the United States to intervene. Another important factor in the United States decision to intervene was the presence of some 1,000 American medical students who could be used as hostages, like a certain situation in Iran.
The invasion force reached a total of 7,000 United States troops, or less than 1% of the United States military (Although far more then the 7,000 were involved logistically of course). A number of Carribean nations also sent troops to assist in the invasion. They discovered entire Cuban combat units as well as a good number of Cuban supplies.
Summary, Cuba helped to overthrow Grenada's democratic government but an invasion by United States and Carribean forces restored the legal government of Grenada.