So what if they can see that you donated to this pro-constitutional defense fund?
If you want to make a surveillance state less effective, you should generate _more_ noise, not less. When fascism is at risk of taking over, you don't just roll over and take it quietly because you fear they'll know you're against it.
As a person who has Nothing to Hide, I encrypt everything, and will gladly donate here. If we get everybody to use encryption, nobody will be suspect for using it. If you donate here, there's less risk that others will get hassled for donating.
1) Find list of people who you don't like (in this case, for legally donating).
2) Perform illegal searches to find things they have done which are illegal.
3) Find another excuse to perform a nominally legal search ("His tail-light was out. I smelled pot, and when I searched him I discovered a large amount of cash in his wallet.")
4) Arrest him for the activities discovered in 2, but allegedly discovered during 3.
tl;dr: Parallel construction allows for politically motivated searches which can lead to 'unrelated' convictions. You will never even know it happened, you'll just be cursing your bad luck.