how can he go back to the original timeline without going through the time machine.

TS...

This is the right one, this explain everything

Lol i dont understand why people so concern about other timeline

For me avengers movie is the only true and real timeline for me ! I dont give a fuk what happen to other timelines

nice try but actually there's no way to properly reconcile the timeline
it's full of plot holes and paradoxes

From this theory, did Cap really get married to another Peggy from another reality?

Since that reality's Cap, which at that point also probably frozen, will definitely also love that reality's Peggy, does this world's Cap really had any business there except to intrude into that dimension's Peggy and Cap relationship? What happens when that reality's Cap is woken up? Wouldn't he be also looking for Peggy as this reality's Cap also did?

While that reality's Peggy still looks, feels and acts the same, she would definitely still be a totally different person to this reality's Peggy.

Is what Cap is doing morally defensible?

don't think so. if steve growing old with peggy is a new timeline, then he would reappear on the machine and not the bench

Steve can use GPS thingy to set time n location to 2023 on that bench after grow old with Peggy in QR timeline

this

i thought the GPS is for the dive and not the return?

GPS for time n location set. The platform for the shrink.

Steve can use GPS thingy to set time n location to 2023 on that bench after grow old with Peggy in QR timeline

don't think so. if steve growing old with peggy is a new timeline, then he would reappear on the machine and not the bench

Flawed.
Why is there only 2 different timeline?
Who ever said there was just 2 timeline?
When they entered quantum realm, there was 3 different destination at 3 different time. Surely they all went to 3 separate timeline. Then Cap and Ironman went back to 1970. Thats a different timeline altogether.

In total, there was 6 different timelines involved. 7 if you include 1945.

It is strongly implied he went back in time and stayed in this timeline and when he was older, he simply went back to the time and place where he originally went into the past and waited.

Might be off topic.

Didnt Cap bring Mjollnir when he went back into time to send the infinity stones. But in final scene at the bench he only have the shield.

Am i forgetting something here?

P.S Why the fark Falcon become next Captain America. Bucky is way more worthy like in comics. Imagine cyborg right arm plus shield left arm. Hnghhh

It is strongly implied he went back in time and stayed in this timeline and when he was older, he simply went back to the time and place where he originally went into the past and waited.