[rout39574]

Something "made fast" is perfectly reasonable usage for tying it in place.

[Riseed]

Yep. And something "made fast" is also perfectly reasonable usage for vastly upgrading its speed. "Fast" can absolutely be a contronym.

[wolfram74]

I think two-word contranyms are more concrete, like "fight together".

Oversight is a less ambiguous example of a single-word contranym.