I think adding “just” protocol detection is fine, although doing a full parser is of course even nicer 
I don’t know much about BT, so not sure what detection should look like. In general the ProbingParser is a bit of a last resort effort as its a bit of code running on a packet each flow, so potentially its expensive, esp if we’d have multiple probing parsers.
We’d be happy to test an implementation and submit it to some trex testing so we know exactly how expensive it is.