Not just Hypex but a lot of manufacturer suggest such stuffs too. That why you can get pre make and DIY on these stuff. Under you see similar thread tabs, you see such problem is very common in ASR. Also you will get 6dB losses, by graph it isn't an issue so Hypex has such a low SINAD. If you get used to hear Hypex in balanced mode, you will notice a less detail presentation with such adapter. Plus possible to induce noise not just ground loop.I would say you may face problems. Most of what I read in that Hypex stuff looked like baloney to me. In most use cases wiring pins 2 and 3 to the RCA plug will work fine. If you have ground loop hum the 100% solution is a quality isolation transformer. Standard mic cables have pin one connected st both ends because A: It is the safety ground for a dynamic microphone and B: It is the return for the phantom power for a condenser mic.
If they think those wiring schemes give all the advantages of a balanced input with an unbalanced source then they don’t know how balanced interconnects work.
If it is not primary source of listening, you can just bet on it.