He is responding to the title, which was not written by the people who designed the spacecraft. The referenced scientific article is titled "A Comet Revisited:

He is responding to the title, which was not written by the people who designed the spacecraft. The referenced scientific article is titled "A Comet Revisited: Lessons Learned from Philae's Landing". It deals with more mistakes than just the crash. So he is not even in contradiction with the experts.