Well there are basically two things to consider in this case - one of which you already have the answer to:
1. A service port may be designed to not power a device at all that is not recognized as being a flash drive of supported size and format. You already know that does not apply in your case.
2. The power provided through the service port may not meet the requirements of the device. This you do not know for certain. Even though it has been working for you for a short time, you do not know if it is actually providing full and continual power. The service port is not meant to provide continuous power to devices and is only meant to provide enough to power small flash drives for a few minutes, so the TV can be manufactured so that full USB power is not continuously provided to the service port under all circumstances. That means your CC can be getting constant power fluctuations or be continually underpowered, which is bad for any electronic device.
However, it is only a $35 (or less) device and if it has been working for you so far, you may be fine with continuing to use it - that's up to you. If you have an outlet you can use, I would suggest you do that. But if you do not and it's either use the service port or nothing, then for $35 it's not a huge risk.