Raw opinion,no authority:
Barrels and bolts are very different.
Without getting to longwinded,no machining cutter is perfectly sharp.There is some clean cutting,but some beating,pounding and displacement of metal as a cut is made.And,just as when a blacksmith reshapes metal over an anvil,the metal is reshaped.This may only influence a thin skin of metal remaining under the cut,but still,that skin has stored stress.
IMO,the staging of the operations in barrelmaking can be used to advantage or disadvantage.I like it that a cut rifled barrel can be bored,lapped,contoured,if chosen,fluted, then stress relieved,perhaps cryo'd,before rifling.Once stress relieved,only the gentle process of cutting the rifling and finish lapping remain.
IMO,that may help in the dynamics of firing.
So,IMO,I would approach any machining on a barrel after the barrelmaker has final lapped the bore with reluctance and an acceptance of risk.
Fluting a bolt body,IMO,does not carry the same considerations regarding harmonics and stress.If your machinist is skilled and competent I cannot forsee any problems.
IMO,What are the motives to flute a bolt? Generally cutting weight on an aircraft,race motorcycle,or backpack is done a gram or two at a time,everyplace you can..So,a cumulative effort in weight reduction might be a reason.And,in close fit working assemblies,providing a low spot where contaminants can get out of the way..:"sand traps" can be an advantage.So,in theory,some stroke smoothness or dependability may be an advantage.
But,IMO,the main reason behind it is selling rifles.Its aesthetics more than anything.A look.Eyecatching. High heels,earrings,etc.Bait.Chrome wheels.
If you are into it,have fun!
Me,I am not excited by fluted bolts.