The Massachusetts reference you're citing is the rule as to when a non-resident with Massachusetts-source income must actually file a MA tax return. It is not the rule that defines Massachusetts-source income.
>>A non-resident with MA-source income needs to file an MA tax return only if their MA-source income exceeds the filing threshold described in the reference.<<
A non-resident with no MA-source income has no income tax obligation to Massachusetts.
Massachusetts taxes non-residents only on Massachusetts-source income. The following example is taken directly from Massachusetts' tax regulations, and may help you understand income "sourcing":
Example (5)(a)(1.2). A telecommuter works for a Massachusetts firm, mainly out of her home in Ohio. The telecommuter works a total of 240 days during the tax year, and is in Massachusetts on 60 of those days. Her salary is $120,000 per year. Her Massachusetts source income is $30,000, calculated as follows:
$120,000 x _____ 60_______ = $30,000
https://www.mass.gov/regulations/830-CMR-625a1-non-resident-income-tax#:~:text=A%20non%2Dresident%20...).
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
