Putin did not invade Ukraine till Trump was gone
Correlation does not equal causation. Might as well argue that Putin feared Merkel and only invaded Ukraine once she was gone. Which would be just as absurd.
Trump has so far shown now willingness to even remotely confront Putin on any issue, let alone Ukraine. The idea that the same man who sided openly with Putin over his own intelligence agencies would have credibly threatened Russia is simply ridiculous.
Whatever his faults, Ukraine and Europe were incredibly fortunate that Biden was elected. Trump would have abandoned Ukraine immediately after the Russian invasion, that much should be clear by now.