Nobody is going to be able to make you a promise that there will be no beg bugs in your room. This is a huge issue for ALL hotels and resorts across the country. All it takes is for someone who has been exposed to the nasty critters, to set their bag down on the floor or bed. Then, that bug(s) is there. And yes, it's most likely plural..sad to say.
Disney does their level best to keep the rooms bed bug free. But, if someone brings them in, with them, then it's next to impossible to check for them until they have started to multiply.
Why is it such an issue all of a sudden? The US has prohibited the use of the pesticides that are most effective in the bed bug fight. Evidently they are quite toxic, so alternative methods have been tried. Those methods are only so good.
My advice is to check out your room before bringing in any luggage. Pull the sheets back and check along that corded area on the mattress, check the seam areas...look for little bits of brownish red..that will be a tell tale sign of bugs. Look behind the head board if you can...along the baseboards. You are looking for that reddish brown color. If you see anything that bothers you, go back to the front desk and ask to have your room changed and tell them why.
My dd has had two situations with bedbugs at camp. Last year, they had had them earlier in the summer and had been promised by the exterminators that the bugs were gone. Well....thank God we got there early and my dd grabbed the bottom bunk because two days later her roommate (one of them) had itchies all over her. Massive number of bites..everywhere on her body. My dd had them 'only' on her upper arms and shoulders. Seems they were in the top bunk. Those kids were taken to the showers immediately, they gave an outfit to the counselors to be washed. When they got out of the showers, they were given the clean clothes and sent to another bldg for the rest of their stay. Every single thing they brought to that room with them went through the industrial washers/dryers...even her stuffed Corduroy (yes, she's 16 but Cordy goes everywhere with her). They were not allowed back in that area of the bldg for the rest of the month.
Like I said...it's very difficult to get rid of them. I think Disney handled it very well for you. I would just tell your son that Mickey and Minnie have taken care of the problem..and isn't it a good thing they took care of it and not Goofy????
Like I said, you can let the resort know of your 'issue' but there isn't much they can do.....in order to do what you need, they would have to exterminate a room, let it breath and then hold it empty until you got there. And even then, with the products that seem to be in use now, there is no 100% promise of no bugs!!