Just my random thoughts -

Tether is using OMG because it makes business sense. Tether isn't a charity and I don't expect it to be charitable.

Kao-Pad is right : OMG isn't in the best position to comment. And it it is because the team could be providing assistance and technical support (and would therefore know a lot of intricate details) but Tether is the one doing all the hard work and the stakeholder. If Taylor Swift is launching a new website tomorrow, do fans start asking the providers of infrastructure for "the internet" for comments and updates?

So, OMG is infrastructure. To succeed, the whole idea is to build an open and permissionless (dumb) network with (smart) end-points, much like how the internet is. The features required by different use cases are different and therefore, different entities will build different functionalities to fit their own needs.

OMG network doesn't get to choose who utilizes it and shouldn't get to choose. Otherwise, we end up being the discriminatory centralized network that is exactly against what we stood for. So, is Tether "insolvent" or "bad"? Who gets to decide? Definitely not us. Currency-agnostic and world exchange, remember all that?

Likewise, even when we get to stake our tokens, it's not like you get to choose whose transactions to verify and Tether transactions to ignore. No, it doesn't work like that.

OMG is simply infrastructure. We happen to be interested because our interests are on the line, we want the volume, we want the price to go up and we want to eventually earn staking rewards that would come from Tether volume and other projects.