The rule really seems designed to preemt spam or unfair/innapropriate advertising practices, not stifle advice when appropriate or conversation in general.
There are federations, where you can ask for player valuations - so its just a matter of WHERE the request is posted. To me there is no harm done if sb. posts a number he thinks might be a good value for a player - who would be harmed by that? I don't know.
Also there could be a sticky thread in the forums, where those questions can be asked, not so sure if that would lead to a huge spam problem...
Manon does not know why this rule is in place and if Marin does not know either - which might be likely - we'll never find out.
@OP:
Both players are somewhat mediocre, if you can sell them for a decent amount, that allows you to get some finished products that'll help you promote, I'd go for it.
Größter Knecht aller Zeiten aka His Excellency aka President for Life aka Field Marshal Al Hadji aka Lord of All the Beasts of the Earth and Fishes of the Seas aka aka Conqueror of the Buzzerbeater Empire in Europe in General and Austria in Particular