Pipe splitting into two halves throughput even if one path is blocked

I feel your pain; I wrestled with this issue as well, and it also applies to plumbing. It's annoying, but I'm so sure it's really a bug. The solution to your issue can be expanded and provides some really nice functionality that I hope they would not fix.

The solution is to tap into the main trunk line using typically a bridge or a valve. The attached image shows my main oxygen line (flowing left to right) with a tap via valve. The valve is limited to only 200 g/s, and you can see the oxygen is decreased on the right and not alternating.

This is great for lines that do not draw a lot as it only siphons off the amount needed to support the line, like your exosuit line.

The downside is that it will siphon off the whole trunk line if the demand is high enough, leaving everything downstream on the main line empty.

Bridges also work to selectively ADD to a line as well. I love this aspect of bridges. Essentially reversing a distribution scenario to an accumulation scenario, a branch will only add to the trunk line if there is space. I do not have an image, so I will try to explain with a little math (oh my goodness, what is he thinking!? j/k):

Branch 1 flow rate: 500 g/s
Branch 2: flow rate: 800 g/s
Output: flow rate: 1000 g/s: taking 500 + 500 the first tick, 200 + 800 the second tick.
Average Branch 1 flow rate: 350 g/s
Average Branch 2 flow rate: 650 g/s

Now, add branch 1 to branch 2 via a bridge:

Branch 1 flow rate: 200 g/s
Branch 2 flow rate: 800 g/s

Hopefully that helps.