I propose this block be U for reasons below:
1. In general, many code points where GC=So and Script=Common are used in East Asia as U code points.
2. Current CSS recommends such categorization too (although it excludes Latin-1 Supplement and Letterlike Symbols, which is somewhat problematic though.)
3. This block contains several EAW=A code points, so existing contents are likely to use them (see histogram from aozora.gr.jp.)
4. CSS text-emphasis property uses these code points in upright form. The spec defines such marks are always upright. It doesn't define orientation in text, but it's an indication of these symbols used as U.
We could pick up code points that are only important for East Asian, but that may lead inconsistency, so I think making the whole block to U works better.