\setuphead[section][alternative=text,command=\SectionCommand,distance=0pt,insidesection={\blank[overlay]}]
\define[2]\SectionCommand{\inmargin{#1 – #2}}
\setuplayout[backspace=4cm]
\starttext
\startsection[title={First}]
\input ward
\stopsection
\startsection[title={Second}]
\startitemize\item One\item Two\stopitemize
\stopsection
\startsection[title={Third}]
\starttabulate\NC Knuth \NC \input{knuth} \NC\NR\NC Tufte \NC \input{tufte} \NC\NR\stoptabulate
\stopsection
\stoptext
Wolfgang
\setuphead[section][alternative=text,command=\SectionCommand,distance=0pt,insidesection={\blank[overlay]}]
\define[2]\SectionCommand{\inmargin{#1 – #2}}
\setuplayout[backspace=4cm]
\starttext\startsection[title={Okay with text here}]
Text here
\starttabulate\FL \NC Knuth \NC \input{knuth} \NC\NR\NC Tufte \NC \input{tufte} \NC\NR\stoptabulate
\stopsection
\startsection[title={Fails with no text}]
\starttabulate\FL \NC Knuth \NC \input{knuth} \NC\NR\NC Tufte \NC \input{tufte} \NC\NR\stoptabulate
\stopsection
\stoptext