Back office admin to industrial associate?

Do you mean transaction admin at top 4 brokerage? Supporting investment sales, leasing, both? 

Regardless, people start in all sorts of positions, they get deleted or omitted from resumes and LinkedIn profiles not long after they get their "real" jobs. So, is a back office job not great compared to a front office job? Sure, I guess. Is it better than one in food service? Yes, your goal of gaining industry knowledge and internal networking are legit. To be clear, they (or their competitor) will not hire you because of this job/title, you need to fight your way into the role you want, but no different than anyone else looking to "get started".

Final point, somewhere in the future (how soon is a function of your aggressiveness), you need to get a true job that gets you "in the game", even if at a "lesser" firm. If this is meant to be a strategy to get pulled into a "top 4" (I'm guessing you mean firms like CBRE/JLL/CW/Newmark), I am not sure it is any better than getting a job at a second tier firm and moving up via performance. Again, you have to know your path, and if that is this job now, then so be it, doesn't mean this is your job in a year or two!