I think it’s nuanced

I can see an argument that Google is requiring you to enter into a separate agreement with them (the terms they require you to agree to when using Google Forms) to request access to the GPL licensed source.

You do not enter into an agreement with the vendor of the software the postal service uses to sort your mail.

Don't they force you to sign up for a Google account to be able to gate access to a Google Drive file?

If they do force you into google forms and you can't send a letter then that's a potential issue.

Making you run javascript is a weaker argument...