As an IDE and compiler etc racket definitely appears to fit within one of the supported categories for classic confinement as per Process for reviewing classic confinement snaps.
In addition though, a snap must also have a requirement for classic confinement via the need to execute arbitrary binaries from the host, or access files outside the snap’s mount namespace from the host (eg. /usr/ etc) - however in the linked issue, the underlying problem seems to be that racket wants to access the emacs configuration for racket-mode - so I wonder if this could be solved by granting racket personal-files access to ~/.emacs.d/elpa which is the standard location where emacs packages are installed?