If filling out the source code request form via Google Forms and/or accessing the download link via Google Drive requires the requester to run non-free (or at least non-GPLv2) JavaScript, then maybe it is in violation of section 6 of the GPLv2 ("You may not impose any further restrictions on the recipients' exercise of the rights granted herein") since the requester is then required to accept an entirely different set of licensing terms and conditions.
I believe section 3.b and 3.c are the rights this is referring to, where you can request the source, and even be changed for the physical act. Suggesting this extends to the license of the implementation of their contact system doesn't make sense. No method of contact, except physical, is going to meet your requirements, including sending postage, where the software used to sort your mail is not GPL.
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.
Making you run javascript is a weaker argument...
Is that the permission they use? Who knows? But it’s at least possible.