It's not, he's simply pointing out that there's even bigger scam out there. That's not the same thing as defending Tether.

It is defending Tether, because he is wrong. Some things are worse than other things. Fraud is worse than the Fed. No one sensible would claim the Fed is as bad as, say, Bernie Madoff.

Formally, his tactic is known as “whataboutism”

> No one sensible would claim the Fed is as bad as, say, Bernie Madoff.

Give it a couple of decades.

Making comparisons to a perceived bigger problem is a defensive statement. The implication in this kind of comparison is that because Y is worse than X, that somehow ameliorates the harm of X. This is reinforced by the "who cares" remark.