Well now! The proof of the vegan pudding is in the pictures! There is no sign of flas, no reflection of flas in the subject's eyeglasses, no flashback from what seems to be a mirrored wall behind the bar or counter area. The wide aperture and shallow depth of field on the close-up is another clue. The EXIF data indicates no flash! The uncorrected WB indicates ambient tungsten light.

The atmosphere in the restaurant does not look intimate, romantic, or quiet so folks celebrating, taking pictures, etc, does not seem out of order. There is a speaker enclosure in the image so there was probably some music. The folks at the other tables seem to be engaged in lively conversations.

So...the OP was wrongly accused of disturbing anyone with flash and therefore was deprived or at least interrupted of the enjoyment of his evening. The restaurant staff did not handle the situation properly.

Happy Birthday! See quick edits!

Flash can yield excellent results if the proper techniques are employed. The "deer in the headlights" red-eye, flat lighting, overexposed foregrounds, and "black hole" backgrounds are mostly caused by a speedlight, mounted on the hot shoe and directly aimed forward without any modification or fine technique employed. The problem is, no one-trick will work in every case and a bit of study is required........

.......I woud like to set up a special flash section on UHH but right now the other sections I manage and co-manage are not heavily trafficked so I don't know if there will be very much interest

Flash can yield excellent results if the proper techniques are employed. The "deer in the headlights" red-eye, flat lighting, overexposed foregrounds, and "black hole" backgrounds are mostly caused by a speedlight, mounted on the hot shoe and directly aimed forward without any modification or fine technique employed. The problem is, no one-trick will work in every case and a bit of study is required to grasp the concepts of the angle of incidence, the inverse square law, and the basis of lighting aesthetics as well as basic exposure concepts that have to do with electronic flash usage.

This is just a partial list of techniques and points that need to be applied as well as a few mentions of special equipment and accessories: Use of a special bracket to enable the on-camera flash unit to be placed about 12" over the lens in both horizontal and vertical orientation. The use of modifiers, ceiling and wall bounce ounce, partial bouncer, off-camera and multiple flash- just to name the basics.

I woud like to set up a special flash section on UHH but right now the other sections I manage and co-manage are not heavily trafficked so I don't know if there will be very much interest

A peculiar thing happened last night. I attended my sister-in-law's fortieth birthday party. It was a nice vegan restaurant in Williamsburg, Brooklyn. We had a great time laughing and chatting amongst ourselves (party of 8). As the photographer I set my camera on Manual, dialed my ISO to 25600 and fired away. Excellent photos of all of us and the restaurant surrounding. Our waiter came over to me. He told me that my flash was disturbing the couple next to us. I paid him no never mind. I kept photographing. A shot while later, a waitress came over and told me my flash was annoying others. I pulled her to the side and showed her my camera. I didn't have a flash. She was confused. Others at our party had their cell phones working in full view. A restaurant manager came over to ask me not to use my flash. I showed him my camera and told him I have been photographing when these kid's grandparents were in diapers. I'm not some ignorant snapchat child !
Any how I enjoyed my meal, took photos of my sister and everyone else at our table and just wondered. Are the Millennials here so self absorbed that they aren't paying attention to anyone but themselves? I felt I was being constantly assaulted because I was using a "camera" and not a cell phone.
Does anyone have their take on this or has anyone experienced a similar scenario?

Happy Shooting!

I have learned a simple lesson in life. I usually believe I am correct on my facts and often will try to prove when challenged. However, when a waiter, waitress, and then the manager stated the same, maybe it is time to look in the mirror???

Just because younger ones do not know the difference between an AF light and flash unit, or whatever you had disturbing them, does not mean they were wrong. They were entitled to a peaceful dinner more than you were entitled to continuously taking photos inside a restaurant.