[carpdad]

If rafters are conventional and nothing else is supported by that wall. I would assume too and what can single width wall support? Still, I think it would do away with all doubt by cutting away small strip of ceiling drywall and make sure the rafter is same as others (assuming). If yes, then frame as you want without the header. Too bad that switch prevents you from getting rid of the whole thing west of the post for beam.
If that is a light switch (another one on the post?), is it possible to add a remote receiver for light fixture power cable and use remote receiver and switch? Maybe just add an outlet at the ceiling and change the light fixture into plug? Remote switch does need battery but with lithium replacements for conventional batteries, I think the batteries will last longer.

 

[Nealtw]

If this is a full length 2x4 is it is worth looking deeper,
If it is just blocks between studs I would install a header with 2 jacks under each end.

All the studs under the beam and ones right beside it should not be touched.

 

[nmp5159]

this is a close up

 

[Nealtw]

View attachment 670538

this is a close up

We would expect a rafter above that and all is fine but if we were short of rafters that day a join over the wall would pass inspection. So you would have to open it up so you could inspect the rafter over the intended hole or just add a header.
If you found a join in the rafter, you might just sister a piece to it.
If the rafter is good all the way, you could open it right to the ceiling.