[1] Citizen's United has benefitted Democrats more than republicans: https://www.nbcnews.com/politics/2020-election/democrats-use...
[2] The second amendment is a constitutional right. A textualist right wing Supreme Court would outlaw any restriction or regulation on firearms whatsoever. That would be entirely consitutional.
[3] There is no contradiction to the logic you describe. There is constitutional right to keep and bear arms. There is no constitutional right to an abortion. Even the supporters of the outcomes of Roe vs Wade admit it was a lousy opinion (e.g. Ruth Bader Ginsburg: https://www.law.uchicago.edu/news/justice-ruth-bader-ginsbur...).
If you want to create the right to an abortion, pass a law. If you want to repeal or modify the second amendment, persuade your fellow citizens to pass a constitutional amendment. An actual, activist right wing court could find most of the federal government unconstitutional, using the same logic Alito used in Roe vs Wade.
There are something like 3000 regulations on firearms in the US which the court has found to be consitutional which is debatable. Most of the Federal goverment, especially regulatory agencies are probably unconstitutional. Social security is probably unconstitutional, as it should be relegated to the states. RICO laws are unconstitutional.
If you create rights by judicial fiat, don't be surprised when they are removed by judicical fiat.