Yes, having RC4 enabled is now an instant PCI compliance fail as it has a die-die-die RFC and as a result NIST changed it, on request, to a CVE grade above a 4.0 - https://tools.ietf.org/html/rfc7465 - https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2013-25... - web browsers have already started turning it off.
I worked for a small credit union, and we were beholden to our state auditors, FFIEC guidance, and the like -- but PCI simply wasn't a thing we worried about.
I'm not sure what I can say except not every bank seems to share that view (although as said in other comments, quite a few banks do indeed have paleolithic systems in unexpected places, and that tends to extend to their security practices - I am not able to name any names, but I can wave in the vague general direction of things which involve VAXen, COBOL and DES-and-I-don't-mean-3DES, all of which thankfully predate me). But I'm not exactly familiar with US banking practices (thankfully): did the credit union just not issue any Visa/Mastercard/etc cards? Huh.
I usually complain when some site uses RC4 and I can't access it, but unlike the OP I don't do that via twitter
(one reason is that I don't even have an account there).
I've sent 2 emails regarding the use of ONLY RC4 on payment sites in my country, and although such emails aren't always acknowledged they did get fixed after I CC-ed their PCI auditors  :)
 which you can find publicly on Visa's site at 'PCI DSS validated Member Agent Weblisting' http://www.visaeurope.com/receiving-payments/security/downlo...
That excuse has gone, on two counts. RC4's now thoroughly toast, and Windows XP's unsupported - and now finds itself without any secure ciphers at all.
It's zmap time…
You might want to get ready to change passwords for sites that have used RC4 in the past. Or, despite as much warning as anyone can give, are inexplicably still using it.