Well, it can be done easily enough with a hack in Kernel/Output/HTML/Templates/Standard/AgentTicketOverviewSmall.tt:
[% RenderBlockStart("RecordTicketTitle") %]
<td>
# <div title="[% Data.From | html %]">[% Data.FromRealname | truncate(30) | html %]</div>
<div title="[% Data.Title | html %]">[% Data.Title | html %]</div>
</td>
We just commented out the div with the Data.FromRealname.
I know this won't survive an upgrade and I should do it in a separate theme, but it's easy to re-do so a can't be bothered.