I would check out a few different solutions. See my guide:
http://www.marketingrockstarguides.com/marketing-rockstars-guide-to-marketo/
And some thoughts about this situation:
http://www.marketingrockstarguides.com/my-big-problem-with-lead-scoring-322/
I treat Demographic Scoring as a base and a filter. Generally I would prefer that in your MQL flow, you exclude any undesirable leads regardless of score.
Yes, your negative demographic score can help with this, but I use this score as a baseline. Demographics are a FILTER that prevents non Buyer Personas from reaching sales. Behavioral Scoring helps determine if your buyer is engaged/close to buying/etc.
In otherwords, if a Student has a high score, who cares? You are going to block them anyway. Maybe you can help by giving Students a lower score like -500
Your Demographic scoring system should be set as a trigger that says
If ( Lead Is Created OR Data Value Changes) AND Job Title = VP
Change Score +15
Lead can flow through ONCE.
Another flow can handle Job Titles without VP.
Another flow handles Students and others whom you wlll never call.