Of course the clerks have political bias, just like their bosses. That's one of the reasons a judge hires a particular clerk. Do you think that Justice Thomas would have hired Laura Ingram if she was a socialist, communist, leftist?
Of course they have a bias. However, to use that bias to suggest things like the timing of decisions to coincide with Presidential elections (with the intent of making segments of the electorate angry enough to sweep your Party into office) is more than just being of the same judicial philosophy as your boss.