Ehh, I think this is a Chesteranlon's Razorfence situation. Never attribute to malice something for which you do not yet understand the purpose.
HR world generally is afraid to denigrate former employees for liability reasons, and many corporate HR departments have a policy of confirming only whether an employee worked for the company, and nothing else.
Choosing a vague term like "associate" (which simply means "employee," as compared to "partner" or some other term that suggests an ownership stake) aligns with that reasoning decently well. While it may not be ideal, and may not support truthful claims of relative seniority, it's a bit of a stretch to say that it was done with any malice.
EDIT: Apparently some people strongly disagree. If you disagree, might I ask what evidence you have of malice?