Is there any rule against aluminum foil tape?
Depends on what it’s used for. Typicallly, tape can’t be used structurally (i.e. holding things together) but you can use it as a decoration. I’m assuming this is what you’re asking about. What are you using it for?
That hasn’t been a rule for years. However, there generally is a better way then using tape structurally.
So, what you are really meaning to say is,
“I looked in the rule book, searched in the rule book, scoured the rule book and couldn’t find a rule against tape, yet someone keeps insisting that there is a rule against using tape on the robot. Have I missed something?”
Right? That is what you’ve done… you haven’t just posted here because you were too lazy to actually go to the rule book, and type “tape” into the search box, and see if anything came up?
There were, at one time, rules against using tape on your robot except for very specific, appropriate, applications. But I haven’t seent those rules for several years now… so if you can’t find something in the rule book that prevents you from using it… it’s good. Even for structural applications.
But do take some time to read the rule book carefully… you may find other rules that restrict material usage and it is a LOT better to know about them now than when you get to the competition.
Jason
Checked the manual, you are correct. Years are just blending together! 
The aluminum foil tape I guess seems weird to me - but you cant use it as an attempt to throw off vision tracking either if that was the intent. Otherwise please ignore.