Captain Davis Love III named Woods, along with Jim Furyk and Steve Stricker, as his latest vice captains during a news conference Wednesday at the RSM Classic. The announcement didn't reach McIlroy until Thursday, when he was informed of the decision after an opening-round 68 at the DP World Tour Championship in Dubai.
"I don't know what to think about that, I really don't," McIlroy said, according to the Belfast Telegraph.
Woods will turn 40 next month and has undergone multiple back procedures since his last competitive action in August. With the 14-time major champ sidelined indefinitely, McIlroy questioned what the assistant's role means for Woods' long-term competitive future.
"It's great that he wants to help the U.S. team in any way that he can, and if that's not in a playing capacity, then as a vice captain," McIlroy said. "Just sort of makes me think what really his health is like and how he feels like he's going to come back from that."
While Woods has no timetable for a return to competition, his statement after the announcement indicated that playing for the U.S. at Hazeltine remains a goal. Woods has missed the Ryder Cup only twice since turning professional, in 2008 and 2014.
"I will continue to do whatever I can to win the cup back," Woods said. "Once I'm fully healthy, I'd like to try to make the team too, but either way, I'm very excited to work with Davis, the other vice captains and the players to get a U.S. victory."
McIlroy went on to term Woods as a "good addition" to the American squad, and Woods' inclusion was also described as a "smart move" by Ian Poulter. But Poulter, who knows a little bit about what is required for Ryder Cup success, isn't sold on the notion that Woods' addition will help the Americans win for just the second time since 1999.
"It's an early announcement, but it's not a bad announcement," Poulter said. "I'm not sure a vice captain will give any team an edge."