To answer the thread's title's question in the most general terms, no, not necessarily, but exactly how cannot be determined. For the population as a whole, on balance, it is a good thing, because many more people, in the population as a whole, can handle alcohol fine and only a minority cannot. For those who can handle it, it offers many psychosocial benefits both as individual people and as members of their communities.

The bipolar population differs from the general population very much in that it contains many people with dual diagnosis, who are both bipolar and cannot handle alcohol. For them, it is a bad thing.

Also, some bipolar people take drugs that may interact with alcohol, although the extent of it is not well known and probably should be determined on an individual basis for people who otherwise can handle alcohol fine and want to handle it responsibly. For people who should not handle alcohol to begin with, the step of determining alcohol-drug interactions can be safely omitted.

So the set of people for whom it is a bad thing consists of two subsets: dual diagnosis BP-alcoholism or otherwise unable to handle alcohol + people able to handle it but suffering from negative drug/alcohol interactions.