not pretty but ok

What's not pretty about it? The inline function?

soft_convert_objects can just do this directly right? (or the copy keyword is not functioning)

Currently soft_convert_objects assumes the input is object dtype, and doesn't do such checking. I assume the check could be moved into soft_convert_objects as well (although eg for Block, which has an ObjectBlock, it knows it is ndarray[object], and such an additional check would be unnecessary)

BTW soft_convert_objects is only used for ObjectBlock.convert ATM, so no real harm in making it handle non-object with these extra two lines (though to get effective simplification in the BM code might need to tweak copy kwarg behavior)

ok if would revisit / consolidate logic at some point here.