Is there a clearer image or other evidence including meaning or reading?. It's hard to tell if this is 𫞽, 賽 or something else.

Please see Dr. Lu’s comment and other evidence in the following pdf.

https://www.ccli.gov.hk/doc/wgcliac2018-07.pdf

For convenience, this is from the document cited in Eiso's comment:

Examples of the glyph in other editions of the telegram code book are given in this document:

According to https://www.ccli.gov.hk/doc/wgcliac2018-07.pdf, the proposed Cantonese reading for this character is "coi3", based on the phonetic 賽. Is that reasonable?

The character is included in GB/T 7590-1987 信息交换用汉字编码字符集 第四辅助集. This means that the character ⿰王賽 should be include in the unpublished 信息交换用汉字编码字符集 第五辅助集. Nearly all indeographs in 信息交换用汉字编码字符集 第五辅助集 are encoded but this one was not.

The G-Source reference value should be G5-426A based on Comment #14826 if HE.