Why is TIFF single-channel float + COMPRESSION_SGILOG not supported

[chacha21]

Using a 3 float channels TIFF with COMPRESSION_SGILOG is supported by a wide range of softwares
However, I thought that it was possible to use a single (Y) plane as well.
I have generated such an image with the libTIFF (and can reopen it).
However ImageJ won't open it
singleSGILOG.zip

Before claiming it's a bug or a lack of support : is there a reason for that ? Is such a TIFF not correct ?