some questions on non-speech tokens

[buttercutter]

In non_speech_tokens(),

1. Might I ask why suppress only the first token for multiple-tokens symbol ?
2. As for the assert() statement, why is it restrained between U+2640 and U+267F ?

        # symbols that may be a single token or multiple tokens depending on the tokenizer.
        # In case they're multiple tokens, suppress the first token, which is safe because:
        # These are between U+2640 and U+267F miscellaneous symbols that are okay to suppress
        # in generations, and in the 3-byte UTF-8 representation they share the first two bytes.
        miscellaneous = set("♩♪♫♬♭♮♯")
        assert all(0x2640 <= ord(c) <= 0x267F for c in miscellaneous)

[buttercutter]

1. is it simply because it is the first symbol in the sentence ? but the subsequent symbol will also be facing the same scenario too.