The use of metaphor here is correct. "SIMILE: a figure of speech comparing two unlike things that is often introduced by like or as (as in cheeks like roses).

The use of metaphor here is correct. "SIMILE: a figure of speech comparing two unlike things that is often introduced by like or as (as in cheeks like roses). “She's as fierce as a tiger” is a simile, but “She's a tiger when she's angry” is a metaphor."