I see your point, especially considering the Russia-Ukraine War being seen as a more current ongoing conflict, but I still feel it would have been easier depicting Biden as a war criminal to a western audience (which has been thoroughly propagandized into uncritically supporting virtually every action of NATO and the Ukrainian government and know essentially nothing about the historical context leading up to the invasion) by reminding them that Biden was still commander in chief during part of the war in Afghanistan and personally authorized attacks that overwhelmingly murdered civilians:

Any doubts that he would plow a different path from every single occupant of the White House before he has been put to bed following the admission this week that the drone strike he personally authorized wiped out the family of an NGO worker in the Kabul suburbs.

The killing of 10 people, including six children, was a terrible mistake, according to US Central Command chief General Frank McKenzie this week as they finally admitted that there were no Isis-K fighters present when missiles struck two cars in the Afghan capital in the aftermath of a suicide bomb at Kabul International Airport in which 175 were killed.

But we already knew this. The neighbors of aid worker Zemari Ahmadi knew it too, as they peeled what was left of him and his children from the walls where they had been happily playing just moments before.

Those dismissed as “collateral damage” had names. Zemari Ahmadi and his children Zamir (20), Faisal (16) Farzad (10); Ahmad Naser and his nephews Arwin (7), Benyamin (6) and Hayat (2), and two girls Malika (3) and Somaya (2); murdered by the US state.

The aftermath was described as a horror scene with “human flesh stuck to the walls, bones fallen into bushes, walls stained red with blood, shattered glass everywhere.” They were only able to find the legs of ten-year-old Farzad.

You’re going to be in an uphill battle trying to convince westerners that Biden is a war criminal for militarily backing a country that has been invaded by a larger power, one that has been depicted by the western media and politicians for years as uniquely evil and responsible for their socioeconomic and political unrest. At the moment it does appear that the invasion may have accelerated the transition more towards a multipolar world order (hell, even an inter-imperialist capitalist multipolar world order may very well be preferable compared to the hellish nightmare that the global south has suffered under with the US-led unipolar capitalist order, as Russia’s interactions with the third world are generally at the very least a much lesser evil despite also being a reactionary capitalist oligarchy), but the invasion has also greatly boosted support for NATO across Europe and resulted in two more countries likely being admitted to NATO (how great the impact that this has I suppose is debatable). Some of the western imperial core's actions during this war have predictably backfired, like the sanctions, but a lot of this still remains to be seen.