Before the benefit of having Matt state his intent for the rule, lets look at the apparent spirit of the rule:
- As a Psi Corps player, you notice that there are two similar results in the refit table. You ask yourself "what's the difference?" You note that the difference is that one says it doesn't stack, whilst there's a rule at the top of the page saying that the results stack unless stated otherwise.
- If there has been a mistake and HEL Track doesn't stack, it is now the same result as Adv Sensors. From looking at the other refit tables, you note that they don't have duplicate results.
- IIRC, the fluff for the HEL Track is that it is a new technique for seeing past stealth that promise to be drastically more effective than just upgrading the power of a standard sensor array.
After thinking it through for a moment, you see that the rule has been written as intended, or the writer has screwed up not once but twice - once in forgetting to state that the rule doesn't stack, once in slipping a duplicate result into the refits table. This is backed up by fluff suggesting that HEL Track has the potential to be better than a simple power-boosted array in the long run.
Most people I deal with would think that the spirit of the rule in this case is more likely to be that the writer hasn't made any mistakes, and the rule as written is correct. I personally find it kind of sad that you suggest that the spirit of the rule is to assume that Matt has screwed up twice unless he specifically states otherwise.