I subscribe to his column and I've read his criticism of Michael Lewis/IEX, so his snark is obvious to me. But I can see how this article in isolation might not convey that.

Yep. Levine's opinion of using the term "front-running" like that is made more explicit here: http://www.bloombergview.com/articles/2015-07-07/can-you-rea...

Liberately quoted:

'[...] man, remember when "front-running" meant something? [...] But then came "Flash Boys," [...] And now, basically any time anyone trades on public information before someone else, it's "front-running," [...]'

Perhaps it's time to start calling what Michael Lewis mislabels "front-running" as Lewis-running.

I've seen this type of behavior described as "order anticipation", which I think is a much better term. "Front running" means that you are using confidential information that an order will be submitted. "Order anticipation" means that are you using public information and you are anticipating that an order will be submitted.

One of Matt Levine's consistent themes though is that there is often a very fine line between 'just reacting quickly to public market information' and illegal insider activity, so the scare quotes may be intended to imply a degree of 'you decide if you think this is completely above board'.

No, there is rarely a fine line. It's a very obvious line of "are you trading on information on the market". An HFT doesn't even have the ability to front-run unless they are also providing a brokerage service.