Because Halliburton got the contract back during the Clinton administration--it expires next year, IIRC. They had already bid on the contract and won. Next year, they're up for a recompete.
many X halliburton employees are now working for the government as consultants and decision makers for who get new contracts..... makes me think... should make everyone think
If they're consultants, then they're not government employees.
If they're actually making decisions, then they are obligated to sell their Halliburton holdings, and if they are (as is likely) political appointees, they are required to put their assets into a blind trust, where they have no idea what their money's invested in.