Defining Massachusetts source income as 'all wages, salaries, tips, bonuses, fees and other compensation which relate to activities carried on in Massachusetts, regardless of where or when the compensation is paid' makes sense. If 'activities' are not carried out in Massachusetts because the employee is doing them in the state he/she lives and works, the income is not taxable by Massachusetts.
The issue is when this definition changes arbitrarily by the state.
I am not required to work at home in NH, I elect to. I am assuming you also choose to work from home, as the commute to Boston would be unfeasible. Your employer is not requiring you to work from home, you chose to do so when you took the job, right? How would we identify whether the employer or employee specified the arrangement, and why would it matter for tax purposes?
One thing I would confirm with your employer is the reporting of wages to the state. If the company is based in Massachusetts, It is possible that your wages will be reported to the state (as everyone else's are) and they will want to know why income tax has not been withheld/paid.
