I'd have heated it up, but only because I wouldn't like to eat cold bolognese so I doubt my DC would.
Sod all to do with food safety. I think the heat until piping hot (how hot is piping hot anyway) is to make sure it's thoroughly reheated, not just brought up to body temp which is a nice temperature for bacteria. Cold with an ice pack will be fine.
I made a spag Bol yesterday, and filled three little pots for my 8mo. Two went in the freezer, one in the fridge. Today I popped the fridge one in a cold bag with an ice pack and fed it cold to DS when we were out. I've been checking on the internet to see if this is safe, and all the advice is to reheat until piping hot. But is this just because they assume you will be eating it hot, not cold? Grateful for any advice!