I think you're putting far too much emphasis in this junior vs senior stuff. Given the fact that a job search can be exhausting for many, nobody's got time to kiss the a-- of every recruiter that they're in contact with. This doesn't negate the need to be polite, but consider the chance that for this applicant, you're just one more name in a long list of lukewarm opportunities. I'm sure yourthe job posting doesn't indicate how long you've worked on your job -- should the applicant treat you differently based on your seniority?
What more were you looking for? Supplication? Bowing and scraping? You mentioned that the applicant contacted you a "few weeks ago" (no distinct number) and I'll say that for someone about his/her business, a longer span of time with no feedback could easily be considered a cold lead. The short response is for sake of efficiency.
I respond often here to applicants about not getting hung up on recruiters, namely because there are ten times more staffing agency recruiters than in-house recruiters, and the former group -- paid on commission -- tends to make lots of empty promises and waste a lot of peoples' time. I've even had staffing agency recruiters call me up and recommend that I spend a few hours reformatting my resume, even in the absence of a bona fide prospect. What nerve!
In summary: cut the applicant some slack; stop taking things so personally; and realize that the applicant has no duty to play the "hierarchy" game.