Two separate issues: risk to aircraft and people near the runway due to proximity to each other, and interference to the ILS signal.You cannot have anyone work inside the 77.5 during landings and takeoff. You can have people inside the strip (the 150m marked area), up to 77.5 from the C/L, with mitigations. You cannot have vehicles inside the strip during a/c operations.
In the case of OBBI, the protected area is inside the strip. You wouldn't walk in front of the antenna whilst radiating, as there are signs warning you of the radiation hazard in the relevant area, and I doubt that a person would distort the signal. It's a CAT II ILS rated at CAT I due to the inability to protect the protected area outside of the strip.