The oil linked is really a bit overkill for our air gun use....it is fine, but the real deal with it is for breathing.....IF anything gets past the seals it is not going to cause cancer in lab mice in the peoples republic of Kalafornia.
Hydraulic oil has a slightly lower flash point then motor oil, it also has some different additives as well, but we are not compressing the oil and using it under pressure....but again IF it gets into the high pressure side it SHOULD not diesel.....our chinese compressors use rubber o-rings for sealing so it is doubtful anything would happen, the orings would give.
Any 46 hydraulic oil is fine, really you just want to keep it changed when it starts to change color. If you have watched the slingshot channel's review of the compressor the real weak point is no bearing surface on the crank....this is what you want to keep swimming in clean oil.