I'm generally not one to bad talk another agent. So, without getting into throwing stones, there have certainly been some gray areas here. Without hearing both sides, my first red flag comes from the fact that OP did not know if the agent was actually representing the buyer initially. Agency disclosure should happen at first contact...i.e. "Hi, my name is XXX and I'm representing XXX as their buyer's agent." That is a NAR (National Assoc. of Realtors) Standard of Practice that is relevant regardless of state:
-NAR Standard of Practice 16-11:
"On unlisted property, REALTORS® acting as buyer/tenant representatives or brokers shall disclose that relationship to the seller/landlord at first contact for that buyer/tenant"
Then of course, there is the implication that this particular agent is more interested in securing his pay check than his duty to his client. NAR is clear that the agent should always work in the best interest of their client, even if it is not in the agent's favor:
From NAR Fudiciary Duties:
"A duty of loyalty is one of the most fundamental fiduciary duties owed by an agent to his principal. This duty obligates a real estate broker to act at all times solely in the best interests of his principal to the exclusion of all other interests, including the broker’s own self-interest."
That basically boils down to, regardless of compensation (or lack thereof) if his client wants this house, he should help him get it. I completely get the used car salesman references, and understand that a lot of agents aren't doing this, but that is what they're supposed to be doing.