The meme itself implies that the left was adamant that Trump's policy was racist, but now that they are doing it themselves it's all ok. I think the above is just reinforcing the point of hypocrisy (which all politicians are excellent at). The generalization is what makes it comedic and pushes the point home. Much like "kids in cages" was terrible under Trump even though Obama built the facilities and Biden continues to use them to this day. Just my thoughts...carry on...and cheers :)