AT fluid is recommended because it has a similar viscosity and properties to stock fork oil.
Forks need to be run at a specific volume of oil to function properly, adding or decreasing the amount of oil in the forks can make a significant difference to dampening and handling. Adding some random fluid that we don't know the viscosity of can and probably will cause unpredictable changes to the action of your forks.
Not to mention it is a band-aid and not a fix, plus it could swell internal o-rings and cause who knows what else.
Also, are you running AT fluid in the forks, or just squirting this in on top of whatever unknown oil is currently in your forks?
If it were me I'd spend the $25 bucks or so for new seals and do it right.