Should a player be suspended for placing (mage) portals in LFR?

No its funny

Are we sure that what’s wrong is not a poor use of punctuation and grammar?

For breaking what rule? My favorite was dropping Exodar portals in WOTLK right before Wintergrasp dropped.

But see players adapted and autobooted mages who were caught casting a portal while in a Wintergrasp raid.

Adapt not complain.