The audio length is part of the AcoustID comparison, yes. Fingerprint submissions also include the audio length, when the AcoustID server decides whether to group the submitted fingerprint with an existing AcoustID the length is considered. If the length difference is beyond a certain threshold (I think 30 seconds, but you’d need to check the source code for this) then it will result in a separate AcoustID.
But this is orthogonal to the question whether an AcoustID can be linked to a specific recording, and whether such a link is valid. Technically you can link the AcoustID to any recording by including this recording ID as metadata of the fingerprint submission.
Theoretically such a length difference could be valid, due to differences in what AcoustID and MusicBrainz consider the same recording. AcoustID bases this purely on acoustic similarity of the first 120 seconds and overall length. But certain length differences would not necessarily mean a separate recording, e.g. if you just have silence added to the end.
For you example this is pretty sure wrongly linked. I cannot imagine any way how a German informative speech on a CD drive cleaner disc could even remotely sound like Depeche Mode’s “A Question of Lust”. Comparing the first fingerprint of the CD cleaner track with another one for “A Question of Lust” clearly shows no similarity: Compare fingerprints #31226008 and #36308259 | AcoustID