According to Bill Bhatti of the Dirty Sheets Podcast, WWE officials have not been to fond of Rusev as of late because of the decision he made to cut his hair without informing the higher-ups in the company. Bhatti noted that superstars within the company are to inform officials and ask for permission if they want to make drastic changes to their characters.
Rusev w/ haircut
The reported reason that that this was such a huge deal is for marketing purposes and the amount of money WWE invest in it. Bhatti noted that Rusev cutting his hair has to result in programmes, cards, sticker books and action figures etc. now have to be replaced because the company wants the latest looks of their talent for their featured merchandise.
Noted that these are just rumors and WWE may not have an issue with Rusev at all cutting his hair.