I think that any effects from drinking alcohol with aligners in depend entirely on the condition/make up of a person's teeth in the first place - might be completely fine for some, might end up causing problems for others. I drink milky tea (no sugar) and herbal teas and sometimes alcohol with them in, tend to drink a lot of water too and am very careful with the brushing, flossing, water pic routine so fingers crossed!
This is hard enough as it is!