I think you'll find that there are very, very, very few people who have attained high N7 rank by ONLY spending real money on packs. I'd be willing to bet that the figure is very close to zero when it comes to people over 500 N7 level. There is no point in being that level if you're not also going to play a lot.
Why would it use n7 rank for co-op matchmaking? You're compstomping, not PvP, you pick the skill level you want to play at, if the people you get matched with consistently disagree with your choice perhaps you need to revise your choice?
Lastly, I call bullshit on being kicked as host of a white gold geth match playing a lvl 20 salarian engineer. Ignoring the fact that kicking the host is self-defeating if your intention is to actually play the game, kicking the MVP of the main white gold geth strat is silly.
If all else fails just get 3 GAFfers to play with you.