I can't speak for the SDF, but since you are asking about this, you probably already have guessed that this is not intended functionality. As such, I wouldn't rely on this behavior being there forever for any particular product you're developing. I would expect this to be addressed if it ever became a widespread problem.
I now understand that you have to build the transaction yourself using build. Example if anyone else gets stuck:
var b = byte("Hello, goodbye, etc!")
tx, err := build.Transaction(
XDR values must always be a multiple of 4. See the "Basic Block Size" section here: https://docs.oracle.com/cd/E19683-01/816-1435/6m7rrfn9n/index.html
To provide some more details for this specific operation:
"Name" is encoded as an XDR string. This means a 4-byte unsigned int indicating the length followed by the bytes representing the string. As always ...