I'll amend my question to accident/incident...
Whilst I would personally like an extra set of eyes I believe that the "safety" arguement is an emotional one not a real one
Maybe the better option would be to point out the COST benefits of having the engineers around.
Have a look at the delays that result when a pilot delays an aeroplane whilst waiting for an engineer to check something. Quantify that as a dollar amount and make the case using the thing that bean counters understand - Dollars.
The emotion is killing the arguement - no matter how valid the un derlying point may be.
Airsupport - I may have admitted to being a monkey - but at least I understand how management works - and I know that making the "just because" arguement, without providing any objective proof to back up my assertions, will not work in the short term.
It may be that the delays that result from continually waiting for an engineer to arrive to check something that an uncertain pilot has found will make the economics of keeping the engineers around more palatable - but you need a sound arguement to get past first base with the management