I have just looked at the link you gave.

You took the spelling 'write up' and the examples with synonyms from the 'Thesaurus' box. But if you look just a few lines higher up, the dictionary gives 'write-up', which I would regard as the normal spelling.

I suppose that by your comment 'alternative writing' (!) you mean 'alternative spelling'. But then it's very sloppy to present your suggestion as though 'write-up' were wrong and should be replaced by 'write up'.

If wmw provides more support from reputable dictionaries, then this might be worth considering. As it is, I would not support the suggestion.

With noun-verb pairs of this kind in English, it is common for a hyphen to be used in the nominal form (write-up), while the verb is open (write up). This is supported by the first two sources I checked, the AHD and Merriam-Webster online.

http://www.merriam-webster.com/dictionary/wri...

write–up noun \ˈrīt-ˌəp\

Definition of WRITE-UP

1: a written account; especially : a flattering article
2: a deliberate increase in the book value of an asset (as to reflect the effect of inflation)

http://www.merriam-webster.com/dictionary/wri...

write up transitive verb

Definition of WRITE UP

1: to make a write-up of
2: to report (a person) especially for some violation of law or rules

If the original poster has reputable sources that contradict established dictionaries and demonstrate that nominal "write up" is a valid, rather than a sloppy spelling, he could post links to them. Lacking that, I see little reason to put more time into this than he has.

If wmw provides more support from reputable dictionaries, then this might be worth considering.

I don't know why you would say this, when everything in #1 and #2 (and my opinion) is to the contrary.

In any case, not write up in lieu of (as correction for) write-up.