Yea it is disrespectful. And particularly if it is your country. Even if it is not your NA, you can still be respectful of other countries anthems.
It is not disrespecting something at all
to not participate. I am not suggesting a counter protest, just non-participation. In fact it is simply offering greater respect and homage to one's greater responsibility as a Quaker, Mennonite or faith of similar conviction to honor God above all manmade things including nations.
I did not suggest any bad behavior just not participating because it goes against one's core beliefs. There are numerous Christian groups that refuse to participate in public prayer with Jews, Muslim, or other faiths, some even refuse public prayer with other Christian groups with whom they do not share doctrinal unity.
The Lutheran Church Missouri Synod suspended one of its own bishops for participating in post 9/11 public serivces at Yankee Stadium in NYC.
It may not be a big thing for the vast majority of us but that does not mean that it isn't a very very sincere and serious issue for others.
Of course, in my view it would have been more respectful if the US Congress had not co-opted Baptist pastor Rev. Francis Bellamy's "Pledge of Allegiance" and added words that he, Bellamy, specifically, chose not to include and do so over the objections of him and later his family. Bellamy had spoken at one time on why he had not included words similar to "under God" in the pledge. Bellamy had stated that it was so that the Pledge could unify people of every conviction under the umbrella of one nation. With those words now added it does exactly what he wished to avoid.
Many would likely refuse to use the pledge if they knew that Rev. Francis Bellamy was a Christian Socialist. That the words, "under God," are specifically religious in their content is obvious in the Knights of Columbus being the group who sought the action from congress.