The coating means that some folks’ worries about a plastic enclosure being cut apart (ie the glowforge destroying itself) should be allayed. As @takitus said, it is the passthrough that necessitates laser-eye-protection. The empty space which comprises the slot cannot be coated.
If you are putting the Glowforge in a commercial setting in the US, you will want to take a look at the OSHA regs in place for your state and type of business.
OSHA Regulatory Practice. At the present time, OSHA does not have a comprehensive laser standard, though 29 CFR 1926.54 is applicable to the construction industry.
A standard for personal protective equipment (Subpart I) may apply in some cases.
The construction standard 29 CFR 1926.102(b)(2), for eye and face protection, states that "employees whose occupation or assignment requires exposure to laser beams shall be furnished suitable laser safety goggles which will protect for the specific wavelength of the laser and be of optical density (O.D.) adequate for the energy involved."
from your avatar, I would guess you are in WA, in which case you would want to look at supplemental state info for Washington: Labor & Industry: Chapter 296-62-WAC
maybe more, too.
Obviously, OHSA standards do not apply in a home setting, but they should still be considered.