As a Roblox user it is currently impossible to mute a user their status updates without unfriending them. When friending a user their status updates will always show on the designated feed.
I would find it very helpful if either;
Status updates only show if a user is followed and friended
Status updates can be toggled off on a per-user basis
Personally I find it somewhat bothersome if users post an update without any real relevant content that fills up the status feed and obscures potentially more interesting ones.
The only current solution to this is unfriending the person (at least as far as I am aware) which seems a tad harsh if all I dislike is the frequency of their status updates.