It is interesting to notice that the Gaelic name has the "l" sound first followed by the "t" sound and in English it is in the reverse order!
Well several centuries ago it was locally known (in Norn / Norwegian) as Hjaltland, apparently both English and Gaelic decided two Ls enclosing the T were one too many, but each dropped a different one ...
Out of curiosity, why wouldn't 'aig' work?
That would mean he owns Shetland, which isn't too likely. :)