If it's suspended by unistrut on threaded rod it's always bolted to the unistrut. If bolting is good enough for the hanging ones it's good enough for the floor mounted ones.
Be careful about that assumption. A transformer hanging from a ceiling might likely survive a seismic event where the one bolted to the floor does not. For example the hole that the bolt goes through can act as a bolt cutter if the hole is larger than the bolt. The side to side motion of a transformer can hammer on the bolt and shear it off. Bolts are much stronger in stretch than shear. the hanging transformer and its suspension will give in a shaker where the bolts on the floor mounted transformer shear off because it is more rigid.
