With triggers, you can just command this unit to burrow at random intervals to a random location, and then unborrow after a while (which I would also randomize). I don't know though if there is a way to check if there is creep around.
There are two ways, if you cannot find a way to know that:
1) Not recommended, but fine if you need that only for a specific map: define an array of points of your choice and just make the units burrow/unburrow every so often. Pretty easy to do but very dull.
2) Completely random as a base, only with some conditions enforced: within a certain range from the point in which you are (in burrowed situation) and also distant from other units that requires OR generate creep. This require for you to define an action, looking for a random point in certain ranges, and keep looking until one which fits those requirement is found.
This could also make you randomize the unburrow (I assume you want to unburrow only when you have found another destination) and burrow commands, by using a temporized trigger (for example: event -> every 1 seconds of game time) which call the action defined above, without while cycles, for all the existing units.
I hope I gave you some ideas, I can help you more, if you need, this was just a brainstorming. Anyway, if you find a way to find if a place has creep by trigger, you still need to check for random points with that conditions.
About data, I don't know how to make AI in data. It's something I should learn, but never had the chance to.
Cheers!
0.962288686605982
Stuff like this is scary. Seems like this person had many dreams and passions that were shattered due to false promises and lack of simply basic real life resources. Although that being said. Working for Blizzard might not be as pleasant as it seems. They are likely to be very demanding of their workers. For me it would likely feel just like what it is: A job.