Helpful Stacker
It is very likely easyJet are, as they should be, adhereing to IATA Dangerous Goods guidelines in this policy. Or, if they have introduced this policy on their own, it is probably as a result of a leakage on board a flight which may have damaged passengers baggage or contaminated the aircraft hold.
easyJet, will normally do their best to carry passengers goods and I suggest you contact them direct with the specs of the brake fluid you use. They will/should check the DG Regulations and advise you if you can take your bike or at very least, explain the reasons behind their policy.