“If you have very large panels of any kind near a political VIP the view of security is they’re a hindrance to the provision of good security”
And that justifies taking the sign??
I’m not sure it JUSTIFIED seizure of the signs, no.
I think it’s inevitable that the subject considers him/herself as the victim of a small robbery.
If they have enough time in many cases they ask the subject to move further away, and keep their sign.
If, though, such signs suddenly appear very close in, the reaction is very strong and will become stronger if the person shows very strong disinclination to relocate and or to surrender the sign(s).
This has happened numerous times to freepers, and in one case very long ago the Freeps were confined behind barbed wire about 1/4 mile away from the VIP appearance.