ldd is not the dynamic linker, it's only a tool to debug the process of dynamic linking. The dynamic linker is ld-linux.so (exact name depends on glibc version, architecture, etc.)
Also, I think the linked article [1] about the security of ldd is somewhat useless. The ldd(1) manpage [2] is very explicit about the security of ldd and tells you not to run ldd on untrusted executables:
> [...] Thus, you should never employ ldd on an untrusted executable, since this may result in the execution of arbitrary code.
It's a little amusing how the linked blog post explains how to create a malicious executable that runs arbitrary code when inspected with ldd, noting that "I researched this subject thoroughly and found that it's almost completely undocumented. I have no idea how this could have gone unnoticed for such a long time." and concluding with "Never run ldd on unknown executables!" - all while the manpage literally mentions that precise known limitation in the third paragraph!
To be fair, you could argue that this limitation is not widely known and people should be made aware of the risks of ldd, but on the other hand you can hardly criticize ldd when its manpage is that explicit about the issue.