Okay, so ArcLight Cinemas just texted me the following official response after I lobbied them a few weeks ago (see prior chain post below):
ArcLight Policies
We look forward to celebrating film with you during the holiday season. The safety of our guests and crew is extremely important. We are constantly assessing the changing environment and taking measures to address security in our theaters.
Accordingly, please adhere to the following bag and costume policies. For the comfort and safety of our guests, we will not permit large bags into the building including but not limited to backpacks, luggage, and large shopping bags. All bags are subject to search and we reserve the right to refuse admittance. We do not allow masks or face paint that covers the face. We also do not allow props (including those that are illuminated) that would be a safety or trip hazard.
Please note that ArcLight Cinemas has the sole and absolute discretion to interpret and enforce these policies to promote safety, comfort, and peace of mind. We realize these policies may cause some inconvenience during the holiday season, but we thank you for your patience and understanding.
We look forward to seeing you at the movies.
Thank you,
ArcLight Cinemas