there shouldn't be any stress on it at all. The jumper struts are pure compression members, and the braces between them must be there only to stiffen them against flopping around on their bases. However if the mast has some pre-bend in it, or the sail battens load the mast forward, then the jumper stays must necessarily be out of line, bending aft a little around each jumper strut since the ends of the mast (and therefore the ends of the stays) are farther aft than the middle. That is going to load the braces in tension since the jumper struts will try to swing aft to align with the jumper stays. I am guessing that is the primary purpose of the braces. They are too long and slender to do much good in compression in any case. If the mast has an inverted bend, then you ought to tune your rig....but they might be in compression.

Whether it is in tension or compression, I think you could straighten it for temporary use, as long as the local deformation stayed no worse than it is now. The reason I say this is that in tension, the deformation from a circular section will make little difference in the tensile strength. In compression these will surely fail in the Euler buckling mode (no, I am not making this up as I go...), not by instability in the wall of the tube ( such as beer can does when you stand on it and poke the side). Euler buckling load is limited by the stiffness of the section, which will be compromised some small amount by the local deformation. You would expect it to fail in compression at that point (especially so since it appears to be near the middle of the length), at a slightly lower load than if undamaged, but not dramatically lower. You would want to get it fairly straight, but it need not be perfect to resist the Euler buckling failure mode.

Is it aluminum or stainless? If aluminum I would inspect the damaged area for cracks. Stainless is pretty malleable, and would be more tolerant.

Having said all that, I like what Brian said above - that a mast is a terrible thing to waste. Obviously the safest course is to replace.

Example: The Euler buckling load is proportional to the 4th moment of area ("I" in engineering terms). Here is a quick drawing of a 1"D 0.049" wall tube with a dent in it. The I is about the same vertically damaged or undamaged, but about 25% less horizontally in the damaged one. It will buckle in the weakest direction, so you would expect it to buckle at 75% of original load. If the member is so marginally designed that it would fail at 75% of design load, then I wouldn't sail the boat even if everything was brand new.