Is it safe to use the ping-zapper trick?
There's no way to be 100% sure, especially if sega decides they don't want us anymore(no proof for or against at the moment), but I have not heard of anyone using it getting banned for using it yet. Like I said before, the people who got banned were using a VPN and from what i read a number of them, potentially all, had made account modifications while on the VPN which would look really shady on sega's end.
What I can tell you is that I along with some people on my friend list and several others have been using it without problems and it shouldn't cause sega to look your way. All their server sees is that it is still your personal computer just with a different IP address which doesn't seem to be shared based on testing with a few friends.
Sega has a terrible history when it comes to communication and seeing as the TOS say we're not allowed to play, they will never acknowledge any problem foreigners are having due to their anti-DDOS measures and if they fix the problem it could take another long while since they seem to like taking their time. Also, if they decide to block foreigners, we'll NEVER know it for sure. When they blocked the south-east asia region they never said a word and never responded to qestions about it, the publisher in charge of the SEA version were the ones who eventually said something about it, probably to get the SEA region players to get on their version.
So the way I personally see it, either you take a chance and enjoy yourself for now, or you wait potentially forever to see if anything is done about the problem, without any solid proof of whether they're even working on it or not or if they simply decided all you're good for is buying Sonic shovelware.
The player base does not have a shred of solid info on the situation(and most likely never will) so don't go believing anything people are saying on the internet about the current situation, people are panicking and throwing theories left and right for now.