It's not so much the Type C connector causing the problem but rather the high data rates of SuperSpeed USB (or whichever one it is that causes the trouble; I can't keep track of the USB-IF's recent garbage). So Type A (9-pin) connectors are vulnerable as well. But given that a BT or BTLE dongle can't really run very fast, I doubt they're using anything above USB HS (480Mbps) and therefore unlikely to interfere at 2.4GHz no matter what the connector.
Yeah, the dongles themselves work fine, it's other USB 3 devices that cause the problem (eg. hard drives or USB 3 hubs).
Bluetooth is also affected by the interference. The advantage of a dongle is that you can use an extension cable and move the transmitter away from whatever is causing the interference.
