I think the article is being a bit misleading.
a) the jacket (of swiss make) contained a swiss army knife - these are not illegal - probably not so in switzerland where I assume TK Maxx got them from.
b) it was a penknife - of which many are sold everyday, and many people carry them (I do as does dp)
c) if a 36 yo man brought one I assume it was an adults coat not a child's.
d) selling a penknife is not promoting knife crime - glamourising that knife and saying 'here go stab someone' is, but not the mere act of selling a well know brand of penknife of which millions are sold every year.
While knife crime is a worry, and while TKMaxx should have realised the knife was in there and sold them with a 18 rating and a warning - slightly misguided, but not horrendous.
Steak knives, bread knives, paring knives, - all far easier to get hold of, most people have them lying around in their homes etc but I don't see people getting worked up about them.