Traxus Industries are a company that had almost completely monopolised the Human market for machinery around the time of the Human-Covenant War. They had facilities on all the Human colonies, including Reach and especially Earth. They were resonsible for the creation of many different types of heavy lifting, construction and transportation vehicles, including the forklift truck.
During the Second Battle of Earth, a Traxus facility was attacked by Covenant and Johnny had to hold off the attack himself. Similarly, earlier in the war, during the Battle of Reach, Traxus Tower and other Traxus facilities were targeted by the Covenant and Noble Team (i.e. Noble Six) was deployed to defend them. It can therefore be concluded that the Covenant were jealous of humankind's shiny forklifts and trucks and wanted to burn them all, to little avail.