If construction debris and material are physically sitting on top of the condenser, you absolutely should not run the unit. That immediate blockage is a huge problem because the unit relies on unrestricted air moving across the top coils to dump heat. Running it in that condition is basicly guaranteed to overheat the compressor within a short time. It puts maximum strain on the motor and internal components, and that is the fastest way to kill a brand new unit. The issue with the dust itself is also serious, even if nothing is resting on top. Dust isn't just dirt; it’s particulate matter that settles deep into the coil fins, which drastically cuts down on the heat transfer efficiency. You might not see the AC kick on as hard, but the system is working much harder to compensate, raising the pressure in the refrigerant lines and stressing the entire electrical system. It is definitly not just a cosmetic thing. When dealing with heavy masonry work, the most effective mitigation strategy is operational control. As you noted, turning the unit off while they are running the saws and moving materials is the right call. But even when they aren't actively swinging the tools, the airborne dust will still settle quickly on the coil surfaces. If you are running it during downtime, consider perhaps keeping a flexible, breathable cover over it when the crew is close by, just to minimize the initial dust load settling on the fins.
It's not always about a single blockage; it's about continuous restriction. Even a thin layer of fine construction dust acting as insulation on those heat exchangers severely compromises performance and longevity. If you're concerned about the lifespan, scheduling the unit to run only when the work is completly finished and the surrounding area is relatively clear of sediment is the safest move for your new condenser.