The Grim Reaper, the black-cloaked, scythe-wielding personification of death, is reading the news of the Supreme Court's ruling. After realizing that better health care will mean fewer deaths (in the short term at least!), he comments, "I'm bummed".
1. In informal American English, bummed means disappointed or annoyed.
2. If a court of law upholds a legal decision that has already been made, it decides that it was the correct decision.
The cartoonist is making an ironic comment on the attitude of those who opposed Obama's health care bill, most of whom were Republicans. His message seems to be "how can univeral health care be a bad thing if it saves lives?".
• Supreme Court Upholds Health Care Law, 5-4, in Victory for Obama (New York Times)