So, T-Mobile fixed their site... again. (it had regressed) Now they're TLS 1.0 only instead of SSL3 only. In reading the full report, I found a minor bug in the "Protocol Details" section. It says:
RC4 Yes (not with TLS 1.1 and newer) (more info)
The server does not support TLS 1.1 or newer, so that parenthetical is not relevant. I think that's in there for cases where a server supports RC4 but only on old versions of TLS for backwards compatibility. In this case that's all there is, so it should just say "Yes" in orange like the other issues.