large independent workflow items can't be used on roxie

When targetting ROXIE, if an independent item is used with size > 10 Mb, then the following exception is produced:

<Exception><Source>Roxie</Source><Message>Dataset too large to output to workunit (limit 10 megabytes), in result (name=wf2)</Message></Exception>

Why is this behaviour different to that of persist items?

If a fix is attempted by changing line 5466 of hqlttcpp.cpp

from
few = expr->hasAttribute(fewAtom) || (isRoxie) || (value->isDictionary() && !expr->hasAttribute(manyAtom));
to
few = expr->hasAttribute(fewAtom) || ((isRoxie || value->isDictionary()) && !expr->hasAttribute(manyAtom));

then the following exception is produced

<Exception><Code>1402</Code><Source>Roxie</Source><Message>Query W20200805-114316 is suspended because assert(numOutputs == 0) failed - file: ccdserver.cpp, line 12131</Message></Exception>