If the LAE wants 3 threads he should have 3 threads. Maybe in this situation its fussing over small things.. .. .As an LAE if I am not happy with something the plane don't go. Just because a bit of paper says something it don't mean it's right. I will discuss matters take advice consult all relevent manuals but if I am still not happy thats it.. .. .We may not have authority to deviate from manuals but we are the people signing the bit of paper and if things go wrong they will wave that signiture in your face and hold you accountable. Our ability to know when somethings not right is quite important, isn't it better to be cautious and go for 3 threads rather than 1.5. Think of the implications if things went the other way round.