I wrote the demo which you reference many year ago for the answer. One can't expect that old versions of jQuery, jQuery UI and jqGrid will work forever.
If one just replace jQuery, jQuery UI to the current one and to use jqGrid 4.6 then the demo will better work, but it will still not work in Chrome. It's well known problems with jQuery UI. The plugin jQuery UI Touch Punch is written exactly for the case.
You can verify that the demo which uses jqGrid 4.6 works already perfectly in Chrome, but not in IE. jQuery UI already works in IE on tablet PC, but sortableRows
works on Chrome and Firefox, but it have problem in IE. Moreover one can see that the form editing dialogs can't be moved on tablet PCs (with exception of Firefox).
The next demo uses free jqGrid. It's the fork of jqGrid which I develop after Tony have changed the licence agreement of jqGrid and started Guriddo jqGrid JS which is not more free. I implemented many new features in free jqGrid. I rewrote jqDnR module used in jqGrid for drag&drop already for the first free jqGrid release 4.8. Free jqGrid 4.9 will be soon published.
Thus I would recommend you just use jQuery UI Touch Punch and free jqGrid to solve the described problems.