A lady can wear a white bolero jacket and taupe slacks to a wedding. In fact, unless you are in the bridal team, you can wear whatever makes you feel comfortable. Weddings are meant to be special for the bride and groom mostly and they are the ones who should really be concerned about what they wear. However, sometimes there can be pressure to wear something more than you like just to please others.
I would say yes if it were my wedding. All I would care is if my friends and family can come. I wouldn't restrict someone because of their clothes! I'd talk to the bride and groom. Everyone is different.
Some would consider it offensive as anyone wearing white would be taking attention away from the bride. I personally dont see how. Remember, you're allowed to wear white after labor day now too so Im not sure this no-white-at-a-wedding rule still apllies.