It is a search and seizure issue. But note that the man was stopped in Heathrow airport. In the UK, as in the US and most other countries, you have to submit to

It is a search and seizure issue. But note that the man was stopped in Heathrow airport. In the UK, as in the US and most other countries, you have to submit to searches as a precondition for air travel. It is firmly established that the government can require you to give up certain rights as a precondition of entrance to certain places. Like going through airport security, or having to go through a metal detector before entering a courthouse, etc. Which isn't to say that what happened here is not or could not be an illegal search in the US. It isn't necessarily a constitutional issue, there are/can be laws limiting what law enforcement can do.