I would have a bigger problem with a player intentionally staying at street rater than squatter. Street is literally homeless, you are living in a cardboard box or under and overpass. You are filthy, half starved, and generally pathetic. You would have to be borderline mentally ill to stay at street if you had money for better, physical hunger if nothing else would drive you. If a player really insists, hit him with consequences. The bouncer won't let you into the club or restaurant for the meet. The Johnson gives you one look and refuses to pay a nuyen more no matter what you roll on negotiations. You get penalties to your healing rolls because you can't get any decent sleep. Want to get really nasty? Don't let them spend karma on anything that requires practice or study, because they don't have the means or the focus to do it. You aren't going to initiate if you are begging in front of the stuffer shack for a mircowave burrito. Another place to hit them where they live- no comlink service for street lifestyle. And everything, everything, they consume, every beverage, water, decent food, bus ticket, cab ride, etc, will come out of their operational funds.
Also, keep in mind that a character who depends on a magical lodge, or external gear like drones or vehicles need to a place to keep them and work on them. Are you a decker? If anyone from under the overpass catches on that you have a honest to spirits cyberdeck they will get ten of their friends and beat you to death in your sleep because the parts from it, broken and split ten ways still fences for more money than they will see in a year.
Squatter I can almost live with as a GM however. A character that is constantly on the move, alternating between living in a vehicle, grabbing a sleep cube now and then, and taking a weekly or twice weekly shower at a truck stop is probably living a squatter lifestyle. You have the same magic lodge/drone workshop issues as the street guy does, and you can't own anything that doesn't fit in the trunk of a car, but you have at lock between you and the world when you sleep most of the time. It has the advantage that you are hard to find. By being constantly on the move you never have KE kicking in the door to your doss (well, maybe not never, its just less likely).
A way to combat both of these conditions as well is to have some playtime devoted to things that happen between runs. Runners have friends, hobbies, downtime activities, etc. If there is no work for a few weeks the street guy is going to get very tired of doing nothing but running from devil rats and eating from a dumpster.
