Hi, to describe the man's clumsy, rough hand with the banch of flower, it can stress the beauty/sweetness/daintiness of the flower more and such the usage it is not unusual at all. 無骨 can also be interpreted clumsy, unmannered, rough, unsofisticated due to context.

It is hard to explain 無骨. I searched 無骨 of a dictionary it says 骨ばってごつごつしていること。 do you know ごつごつ？ごつごつ means rugged; scraggy; angular. 骨ばっている means to be bony; to be angular So my image of 無骨な手 is like farmer or carpenter who especially getting old. Sorry for the bad explaining. Hope someone will explain it better.