If churning was illegal,it would be in the rules, if its not, then oh well, everyone is playing by the same rules, and you have to use them to your advantage.
I've played in a basketball leagues with no games played maximum, i did better with lesser players by maximinzing games played. Normally my baseball league's rules say you can only draft players on the 25 man roster or dl to start the season. Also, besides our 5 man bench, we have a DL with no limit. Many years, people will try to draft numerous DL guys, and then take the best of the remains after the draft, and stash the hurt guys until they come back. This year, due to an early draft, we opened the draft up to all players, and numerous owners tried to draft a sure minor leaguer, in order to stash him until late in the season.
Any good set of rules should try to close all the loopholes. If it doesn't , you can't change rules mid-season without a unaminous consensus. And even that should be only used for freak loopholes and completely unexpected situations.
Currently I am in 2nd, 2 pts out of 1st, and 6 pts ahead of the two teams tied for 3rd in a 5x5 roto league, with weekly transactions and a FAAB budget. Teams 1 and 3a are out of FAAB money, Team 3b has enough left for one player. I have enough left for up to 9 players. As the season winds down, you can be SURE that I will be picking up two-start starters, and/or any other FA who catches my interest (nobody would have a problem with this) and waiving some good players. (the by product of my pickups) As I waive a good player, I will send an email to someone at the bottom of my league to pick the player off of Waivers (done by standings) and hopefully they will pass one of my competition in a category. (i'm sure that some people here will find this "dirty" but that's just silly. I'm just talking to another owner about how to help themselves.)
Making a trade or other moves that not only help you, but HURT the teams in front of or directly behind you, isnt cheating, its SMART.
Its the equivalent of blocking a waiver claim in the MLB.
If you want to make up new rules, go right ahead, and apply them to your league next season. In the meantime, use the ones that exist.
"Baseball is like church. Many attend. Few understand." -- Leo Durocher