I wish you the best of luck getting everyone you communicate with to stop using SMS.

Is that bad?

I wouldn't call it bad, but I would call it incredibly expensive if you're using non-English alphabet.

Try filling out all the characters available within a single message, then replace one of them with something unusual (let's say "ć" for example). What used to fit into a single SMS will now be three.

I'd bet he's implicitly expressing his concerns about SMS's vulnerabilities in terms of security, especially compared to other, more secure alternatives.