Which butanediol are we referring to here? 1,3-butanediol, although by proper definition not a glycol, is the most often used isomer but by far not the only one. Apart from that, butanediols also come as stereoisomers which complicates things even further.
1,4-butanediol certainly is problematic because it’s quickly metabolised to GHB. Therefore, it is a prodrug or at least a precursor and therefore regulated.