Peace Corps bars HIV-pos volunteers?

Just got this release from the ACLU:

The American Civil Liberties Union sent a letter to the Peace Corps today demanding that it change its policy of barring people with HIV from serving as volunteers. The ACLU sent the letter on behalf of a Denver volunteer who was sent home from his post in the Ukraine and terminated after he tested positive for HIV.

Here's the volunteer's story, again via the ACLU:

“I joined the Peace Corps because I wanted to learn more about the world and help people,” said Jeremiah Johnson. “It was hard enough to learn that I had contracted HIV, but to then be shipped home and told I was unworthy of finishing my service was incredibly humiliating.” Johnson, now 25, began his tour as a Peace Corps volunteer in December 2006. He tested negative for HIV prior to beginning his service. For nearly thirteen months, he was the sole volunteer in Rozdilna, Ukraine, where he taught English to middle and high school students. In January 2008, Johnson, who was in Kiev to attend a Russian language program with other volunteers, received a midservice medical examination and opted to take an HIV test. After the results confirmed that he was positive for the disease, he was immediately told that he could no longer work in the country because of a Ukrainian law barring people with HIV from working in the country. He was also told he would not be able to finish his service elsewhere.

Then here's what happened:

Although he had no health problems, he was only allowed to return to Rozdilna for two days to pack his bags and say goodbye to the people he had met during his tour. He was forced to abandon projects that he had been developing to help the community. Johnson was then sent to Washington, D.C., for an end-of-service medical exam. In DC, he again asked Peace Corps officials to explain why he was being terminated and asked if he could continue his service elsewhere, but these requests were denied. Instead, he was given an automatic medical termination, stating HIV as the reason for his termination.

A copy of his termination documents are here. What do we think? Does the Peace Corps have a case for keeping HIV-positive volunteers from certain jobs, or is it blatant discrimination?