In 2009, Barack Obama came under fire from various left-leaning groups when he chose Rick Warren to participate in the Inauguration, despite Warren's views, which included the belief that homosexual behavior is sinful. Obama said he wanted Warren to participate any way, to be inclusive, and he did.
A pastor who has beliefs similar to Warren's and was scheduled to deliver the benediction this time has withdrawn his name after similar protests. I don't have a strong opinion about this one way or another. There are plenty of clergy members, or others, who are well suited to perform this duty.
I don't think it is a must to have this view represented during the Inauguration ceremony this time around even though it was in 2009. I feel the same way about the president's cabinet picks.
This president has already shown his willingness to reach for talent wherever it can be found, no matter race, gender or sexual orientation. He has made that clear in his staff choices, which some are the left are questioning this time around for not being diverse enough, as well as the choice of clergy, which the left criticized for being too inclusive.