Are Supreme Court Justices merely politicians in robes?

The idea that Supreme Court justices are politicians in robes is most surely backed-up by the politicisation of the appointment process. Merrick Garland, a liberal judge, was rejected by a republican senate without even reaching the 'interview' phase of the process. This is because the man he was due to replace, Anthony Scalia, was a hardline conservative. Merrick Garland's appointment would have shifted the composition of the court to the left and as such the court would have had a more liberal interpretation of the constitution. This could be a potential stumbling block for republicans hoping to pass/abolish controversial policies- this shows that due to the huge potential effect supreme judges can have on the law, they can be seen as politicians in robes.