So don't go getting a sleeve of every card from the deck.
It's not just sleeves, it can be any tattoos on your arm. Just like a simple lip piercing isn't allowed for some jobs--it doesn't have to be huge, it just has to be there.
Honestly, I could care less what tattoos people get and where. If they have the opportunity to get a tattoo anywhere they please (ie. their job doesn't get in the way), then by all means they should get their tattoo wherever they want. I'd just think it would be silly to close some doors just because you want to get a tattoo that can be just as nice somewhere less noticeable on your body--that would be a far too emotionally charged decision lacking logical thinking (while it's fun to make decisions for a strong emotional reason, it can be very stupid logically).
In sum: If you can get a tattoo anywhere, then great, go for it. If you think you may want a professional career in the future, you may want to think about where you want to get that tattoo a little bit more.
Whether you take my advice or not, I really don't care. Honestly, I don't care where you get your tattoo, or even how it affects you or your future employability. I'm just letting you know this so, if
you care about your future employability, then you can take more care in your decision. It doesn't affect me any if you have an easy or hard time getting a job.
(note: I'm using "you" in the general sense in this post)