I'd say it's a sign of acceptance. It's good that Veronica understands Momo's differences but she mostly interacts with other humans and human is her default mental model of a person. That she automatically lumps Momo in with the other people she cares about means she considers Momo equal to other people and not something "Other."
Finding out you aren't part of someones default mental model of a person can be an alienating experience. I would consider it an off-the-cuff definition of Othering. I don't think Veronica did anything wrong but she does seem nervous about Momo. It makes me wonder what the QC AI timeline is? (I'm sure it's written down somewhere). Is Veronica not as used to AIs as the people her sons age?
I don't think she's really nervous about Momo at all, she just got a little flustered about making what she perceived as a faux pas when she herself lives what general society views as an alternative lifestyle and hopes others would be as accepting of her as she is of them.
Personally I don't feel she made much of a faux pas in this particular instance though. She accepted and perceived Momo with no prejudice whatsoever, the way I see it, and by offering her cookies treated her no different than the other youngster in the room. It could even, in a way, be viewed as complimentary that for a moment she forgot Momo wasn't a "real girl". The bigger faux pas, if anything, might be that Veronica made such an issue of it afterwards.
I get that some disabled people, or people who are "different from the norm" can get upset when someone appears to
forget that fact, using words like "unfeeling", "unempathic", and "alienating". They want these people not to remind them of their differences, and be mindful to not do anything that
does remind them they're different. That just doesn't feel natural to me.
Personally, when one's friends forget, I view it as acceptance to the point that they just don't notice the difference anymore, and instead of viewing you as "my blind friend", "my wheelchair bound friend", or "my manic depressive friend", they just view you as "my friend".