A salesperson who stands too close to a prospect or leans over the prospect's desk is most likely triggering a:

space threat

Explanation:

The territorial imperative which causes some people to feel or perceive that they should protect or defend their territory or space against the space threats.

In the context, if the salesperson pulls up the chair too close, or if he or she tries to take over all the space or part of the prospect's desk, or if he leans over the desk, or touches the different lying objects on that desk, he or she runs the risk of invading a prospect's space.

answer; a client who is similar to you;