I'm sure Meng singled out the GPL only because it is the toughest to
comply with regarding patents. This is because of its 'no additional
restrictions' clause and the requirement of transferability.
When we released our TSIK code we choose GPL because the poison
pill covenants would stop our competitors making products off our code.
In this case the whole point is to get companies to make and sell
commercial versions. It would not be good if Lotus could not use
the spec.
For the Web specs and code we rejected the GPL and made both public
domain. Getting Microsoft and IBM to build the Web into their products
was a big priority. That could not have happened if the original
reference code had been encumbered.