Well you're entitled to your opinion as I am to mine. I maintain that just because you can shut the entire site - is it justified?
The people at the museum will have zero interference with the investigation. Intrusion is admittedly more difficult to control but the police now regularly use screens at motorway accidents without inconveniencing their investigations, and nobody is going to stand staring at screens for hours while walking between the hangars.
Several people on here have already commented on having seen a video of the crash. It's not been released by any of the regular news sites, why search it out. The people who posted it and those who searched for and viewed it are guilty of intrusion, albeit not in person, but its a bit rich to then suggest that a blanket closure needs to be in place just in case the public might behave in the same way.
Ultimately, how far do you have to ring fence a site. I presume the M11 isnt shut ?