Your tendency towards simplistic solutions is incredible.
Why try and make life complicated when one already knows the history of Lech Poznan supporters group and one is familiar with their modern day slogans and operations?
I wouldn't insult them by trying to pretend that they were attempting to do anything other than intimidate and offend the Lithuanians.
If they were xenophobic (antii-Lithuanian for instance) in the first place, then it woild have been all the easier to instigate such as scene.
I assure you that these things are planned by the very top guys within Wiara Lecha and others. They wouldn't let some random guys instigate such a scene - nothing happens in that stand without it being planned and orchestrated. One thing I highly respect about them is their sense of organisation - which you need in order to produce a massive banner like that.
So far no-one actually knows who was behind it -- spontraneous or inspired from without.
We know who was behind it. The banner was kept in the part of the stadium allocated for the fans use only. Why try and look for a conspiracy where there is none?
BTW did you ever consider who actually ordered, created and paid for so huge a banner?
Huge banners are nothing at all abnormal for ultras in football. In Wiara Lecha's case, they raise money in a variety of ways - they hold collections, they sell merchandise, they make some money from organising transport - etc etc. Banners aren't expensive as well - you can get a 5m x 1m banner for about 90zl. Such a huge banner would attract a big discount - and if the printing company supports Lech Poznan (as many people do) - then they would get it for cost price.