I am an engineer.
In theory, the forces on a LCA are considered to be almost entirely axial (tension/compression). However, in real life, there are bending forces transmitted to the LCA.
The magnitude of the LCA bending forces are hugely dependent on the suspension design and the exact geometry. A McPherson strut suspension is more concerned with small packaging and low manufacturing cost as opposed to optimal suspension performance. Thus, there may be more bending associated with that design than a racing suspension.
With that being said, I looked at some finite element analysis of simple double a-arm suspension designs - mostly because car manufacturers don't publicly publish their engineering reports and racing engineering students do. The analysis showed that the bending forces on the lower control arm to be very small compared to the tensile forces (on the order of 1/100th).
I am going to go out on a limb and guess that Porsche over engineered the LCA and took into account the exact geometry of the McPherson strut so even if there is some bending forces, they are likely to be minimal compared to the tension/compression forces.
What does all of this mean? If it doesn't buckle in tension/compression, it shouldn't be likely to bend.
After you drive it a bit, INSPECT IT CLOSELY. I can't emphasize this enough. Since there is no engineering analysis supporting your design modification and materials selection, you have to verify it manually.
You have to inspect it. You need to check the sleeve for any sign of becoming out of round. Then drive it some more and INSPECT IT AGAIN. You will likely have to
inspect it on a regular basis for the rest of its life because you have no idea of the longevity or durability of this design approach.
With all of that said, I wouldn't attempt your project. Too risky for me. Like Quad said, it would make me nervous.
And like any serious nerd, I am more than willing to cite a good reference:
Using FE Models to Predict Suspension Loads