Hardly.
"bet365 reserves the right to reclaim the bonus element of such offers and in their absolute discretion either settle bets at the correct odds, void the free bets or void any bet funded by the deposit bonus."
If Chelsea or Arsenal win they'd give you the £16.66 profit which you're more than entitled too, yes, just don't expect them to refund your in-play bet as you'd have gone against the terms and conditions of the offer.
Right, so don't place one of your bets on something so good, just in case you win? Yeah, OK, vultures.