The elements of the cage will probably interfere, but won't straight up block the signal. To be an effective faraday cage, holes in the material must be no bigger than 1/10th the wavelength.
2.4GHz wifi has a wavelength of 12cm, and 5GHz is about 5cm...so holes in the cage should be no bigger than 1.2cm for 2.4GHz, or 0.5cm for 5GHz.
I may expect some signal reflection and likely a high noise floor as a result to being so close to a hunk of metal. That'll cause some problems.
Problem #1 is this AP is oriented vertically on a wall. The antennas in these models are designed to be parallel to the floor, and usually not much higher than 15ft.
