cryptomaniac_xx explained that a bit.
mirakal when in doubt remember that google's your friend and by searching anti tampering rule nba the following results were available
https://www.bworldonline.com/nba-anti-tampering-rules/
https://www.msn.com/en-us/sports/nba/nba-investigating-lonzo-ball-kyle-lowry-sign-and-trades-for-possible-tampering/ar-AAN3xoX
As NBA fans we all got to know this rule as there have been plenty of strange cases around that.
I hope these two links will help.

I like him playing back to back with LeBron, this two have that pride which really best to see this upcoming season.

After being criticize since most of them are not in their  primes anymore, and from how I see both  still have it.
Enough playing minutes and a good system to maximized Melo's worth being an asset of the team.

Lakers Fans will love this new line up playing with their Jerseys!

Better than nothing at all, That point of turning down Lakers offer might reflect to him once there's no available contract for him. Else, he will accept Boston's offer and play with them, like what you said he's fit with them since Walker already went out and this team needs a good quality point guard who can also bring some good numbers.

Will wait for further updates from this dude if he'll finally land to a good team that he deserve.

Yes. That's why I don't understand why NBA is stretching this issue like it's not a normal thing that had happened for the past few years.
Here is the full article about the "Tampering" that they are trying to pursue.
https://www.cbssports.com/nba/news/nba-investigating-tampering-allegations-in-kyle-lowry-lonzo-ball-sign-and-trade-deals-per-report/
I'll just put little bits of details on why it is a normal thing that had happened before and the reporters might also have some contribution to why NBA management is looking at it. The early news and rumors they release in social media and their inside sources that feeds them the scoop.

Agree to that, he's still in good shape if he managed not to get any major injuries, if he played and jive well with his teammates Boston might signed him with his dream contract and stay with the franchise.

I remember that, Thomas almost bring them to the finals, but LeBron still dominating the east back then and they don't have the power to stop him.

Thomas career after that injury turned to nothing, he can still play but not that star caliber anymore.

That's true, he really has a stellar season with the Celtics, but that serious injury ruined his future.

2016-2017 season was the best season of his career where he averaged 28.9 points. https://www.basketball-reference.com/players/t/thomais02.html
next season, he played with 6 teams already up to now.

His total earning so far is $31 million - https://hoopshype.com/player/isaiah-thomas/salary/ and that's 8 seasons of playing, while other players only gets that in one season.

Schroder at Celtics will be an orb-effect lol (Dota terms).

Basically, with Jayson Tatum and Jaylen Brown as the leaders there, I hope he will cooperate. Remember that in Lakers, even Lebron James and Anthony Davis was there, he feels he can do anything. That mindset leads him to take down the Laker's superb offers on which is not a good idea.

He thought his value isn't worth $20M per year and basically want more money. Take note, he's not even an All-Star but still expecting some teams can offer more.

That's what I'm talking about, if the Lakers did not offer him the amount he expected, I don't think other teams will make an aggressive offer. With the Lakers, maybe his potential was not yet maximized because he played the same position as Lebron, Dennis Schröder is a point guard so the team has to fully utilize him.

Well, that's true but Tatum and Brown are not on the same level as Lebron who can demand on who's going to be his teammates and can even demand on who is going to be his coach. Maybe one of the reasons is he doesn't want to play with Bron of we called the king.

What's the connection of Lebron James can demand who's going to be his teammates or anything lol.

He turned down the offer because he wants more money. That's no secret. If the offer somehow is $100M for four years, surely he will accept it. Do you really think there are teams who can offer that kind of money to him? Before landing at the Lakers, he is not even a special piece on OKC and only played 14 and 2 times as a starter respectively for 2 seasons.

Transferring to Celtics, he is only projected to have $9 to $10 a year. See what kind of offer he wasted on the Lakers if he sets aside his ego. Anyways, to make it more clear, let's wait for the final contract if ever Celtics will sign him.