Skipping rules are applied based on the order in which the synchronization operation (delete, update, add) is performed for the actual object (directory or file).
For example, if there is a delete operation in the directory, skip rules for files in the directory for the delete operation will NOT PREVENT files from Get DELETED!
In my case, the MySite \ MobileForms directory is completely deleted. The skip rule set for files is useless.
And for the directory, my mistake is in the regular expression:
-skip:skipAction='Delete',objectName='dirPath',absolutePath='.*\\MobileForms\\.*'
Must be:
-skip:skipAction='Delete',objectName='dirPath',absolutePath='.*\\MobileForms$'
which says it should skip deleting the MobileForms directory path (the first rule mistakenly included a slash in the regular expression).
Hope this helps others too.