I down voted your post as off topic/irrelevant.

Posts on /r/legaladvice should be focused on providing constructive information regarding the thread's topic. In this case, you have not provided any information regarding concealment. You have only replied to say another post did not include it without including it yourself. That isn't much more on topic than what you were replying to by your own standard.

If you want to edit the post to contain more relevant or on topic materials, I will be glad to give an up vote. Constructive posts are much better than the one you've written here.

To keep to the topic, concealment is a subjective judgement rather than objective. Someone with a shopping bag could be 'concealing' something by the standards of a untrained, not bound by law security guard instead of a qualified peace officer with arrest powers. The only relevant materials to this opinion are the video tape or hard evidence of this and the determination of the peace officer. The security guard is just a citizen like me or you. They are not empowered by law to do anything you or I couldn't do.

Source: I'm a trained, qualified, and licensed security guard licensed by the State of California BSIS.

The Merchant Rule allows security guards to temporarily detain people who they suspect of shoplifting. We may not do this by putting our hands on the person. We may not open the person's belongings to look inside. We may not take possession of anything we find on the person including weapons or drugs. We are also not empowered to take any measures to ensure someone complies with our detaining them.

tl;dr I disliked the content of your post too, but I also replied with useful information. I hope you follow this example in the future.