the US is boycotting Unesco since the admission of Palestine
I don't think this is exactly correct. When Palestine joined UNESCO, a 20 year old law automatically cut US dues to UNESCO. This was not planned or chosen by the Bush or Obama administrations. Unfortunately, to change this law would require Congress to take the initiative. The US Senate would change the outdated law, but the Republican led House would not. So nothing changes.
In fact, I have never seen the US more involved with UNESCO. There is a World Heritage Blog on the National Park website. World Heritage Week is being celebrated this week. When I visit WHS in the US these days, it is much more obvious of the sites designation. Lastly, the US is currently preparing 3 nominations, all nearing completion. (Poverty Point, Frank Lloyd Wright Buildings, and the San Antonio Missions)
I really hope politics don't come into play here. It would punish the US unfairly, when they are actually fully involved with UNESCO. Also how could UNESCO possibly punish the US after they paid a huge portion of their budget for decades!