This is exactly why I wont register any domain that do not allow whois guard. I would suggest using whois guard, NameCheap has one of the cheapest ones. Alternatively, you can have separate disposable email address on your whois info.
Found it: https://support.google.com/domains/answer/3290350?hl=en
" We include 10 million resolutions per year for each domain you register with Google Domains. "
Question: What happens when you reach 10 million ?
Also found disturbing article about google whois guard:
http://arstechnica.com/security/2015/03/epic-google-snafu-le...