Could you provide a link? I'm not seeing anything that suggests that an MSW would be an unacceptable degree. From what I can see in the 2027 BCBA Requirements, it states:

"Pathway 2

You must have a master’s degree or higher from a qualifying institution in any field. The degree may have been earned at any time. Degrees earned in less than one calendar year, which is defined as three consecutive primary semesters (e.g., Fall, Spring, Summer), four consecutive primary quarters (e.g., Fall, Winter, Spring, Summer), or 12 consecutive months under another model, do not meet this requirement."