Yes, it actually is. No idea why first page states that it's about 2 min when even source code has a 60 sec target:
https://github.com/signatumd/source/blob/master/src/main.h#L73

I configured Signatum node on my server and got some stats:
https://nullspam.ru/nodes/signatum/

Block time deviation from 60 sec is also considered in reward calculations there.