Regarding Biden and foreign policy: My thoughts - let me know what you think about it.

The explanation for why Biden has not spoken with other world leaders is that he can not do it. If someone/anyone other than the "POTUS" himself were to initiate those customary contacts / conversations it would let the cat of of the bag so to speak.
It would raise obvious questions about "WHY" Biden himself did not speak directly with other world leaders.
In that case the American Communist Party would have no other option than to come out and admit that they are running the "Executive Branch" by Central Committee and not by POTUS and Cabinet.

This is the most logical and IMHO obvious explanation for Biden failing to perform his due diligence regarding foreign policy and the obvious failure to reach out to USA long time allies around the globe.