NOLs and rental income from non-active participation

In what context?

Should have read your "Subject". Rental income is included on the Form

Your rental income would be net investment income for purposes of the Medicare Contribution Tax (3.8%).

I realize that the instructions for form 1045 don't distinguish rental income from active participation from rental income from non-active participation. The reason that I brought up the question is that I have this old article from 2009 that categorizes rental income from non-active participation as non-business income. However, nobody else seems to be making this distinction? I was wondering if anybody has any deeper insight into the issue.

The only insight I can add is that I believe that rental losses that fall into the $25K allowable passive loss are allowed for an NOL.