Maybe I'm dumb but... I feel like a red plus sign is too simple and generic to be afforded such strict and special protection. It's almost universally understood that a red cross is synonymous with "first aid" or similar. You can keep insisting that only your brand is "velcro" and all others are "hook and loop" or whatever, but it's a losing battle and eventually you have to accept the ubiquity of the word or symbol.