ID: Drawing of a duck billed platypus underwater, they're wearing a rainbow coloured t shirt and a pink bum-bag, and saying: "Ally is not something you can self-identify as, it's a title that you earn. Let your actions speak for themselves!"
Credit: Sophie Labelle
You're right, it sucks being told how you can and can't identify. The purpose of the post seems to be to motivate allies to take more action to help. But I agree that the phrasing is problematic.
Just keep being supportive of LGBT people in real life and ignore random memes online. I consider wearing a pin as an action that qualifies as an ally. It's looking like LGBT people might need more help than just a pin with the way governments are heading.
Also if you are dealing with people online, consider that they may be bots or trolls who may not even be LGBT purposely attempting to cause division.