Parrots shouldn't consume large amounts of dairy, but a couple licks isn't going to hurt your bird. Keep it at a couple licks though Most birds become ravenous dairy fiends the moment they taste it and will eat ungodly amounts that may very well be harmful if allowed. My mom's birds are all healthy, in their 40's and all consume the occasional bit of dairy (be it cheese, yogurt, a piece of cereal that was in milk, ice cream ext....). There are FAR more 'dangerous' things to feed a bird besides a bit of dairy once in a blue moon. Just use common sense and don't overdo it since it is not a natural food source.
Our old vet actually suggested giving (a little) yogurt every day while Kiwi was on heavy antibiotics to help with the stomach upset. He made it through 2 rounds of antibiotics with minimal weight loss and diarrhea, plus recovered fully from his infection and has been in perfect health since.
I 'used' to think a little dairy would be all right. My Hunter had a recurring Xanthoma on her third eyelid. It was removed a total of 4 times, but kept growing back.
I extensively researched Xanthomas, and stopped giving her (and the rest of the flock) cheese. They all LOOOOOVE cheese, too. The Xanthoma hasn't returned in over 2 years now.
Presently have six Greenwing Macaw (17 yo), Red Fronted Macaw (12 yo), Red Lored Amazon (17 y.o.), Lilac Crowned Amazon (about 43 y.o.) and a Congo African Grey (11 y.o.)
Panama Amazon (1 Y.O.)
I don't give mine ice cream, but I do give them the occasional piece of frozen juice bars, and I do give them the occasional licks of orange/rainbow sherbert.
Sherbert doesn't have the lactose in it. It is, however, high in sugar. So, an occasional taster spoon on hot days is about the most we go...
We also freeze juice on a popsicle stick in an ice cube tray, and give them those as well... Those are outside in the tree things, to save the drippy sticky messes.
Mine get very limited amounts of cheese. It's an occasional treat. Not an every day thing.