Good morning Terence,
This is an interesting question that has several facets to be considered.
Rule #3. Official Terminology and Gestures
Official betting terms are simple, unmistakable, time-honored declarations like: bet, raise, call, fold, check, all-in, complete, and pot (pot-limit only). Regional terms may also meet this test. Also, players must use gestures with caution when facing action; tapping the table is a check. It is the responsibility of players to make their intentions clear: using non-standard terms or gestures is at player’s risk and may result in a ruling other than what the player intended. See also Rules 2 & 46.
Is "I limp" a simple, unmistakable, time-honored declaration like those listed above? In my mind, the phrases "he limped" or "they limped" are very common and unmistakable. It means that the previous player(s) merely called the prior action. Also, the phrase "I limped" is often used as a response by a former player to a latter player's query on the action previously made. However, IMO and experience, it is uncommon for a player to use "I limp" as a declaration of their intended action. (Uncommon, but no completely unheard of.)
Also, the TD could look to rules #45 Methods of Calling and #46 Methods of Raising for more information. For example, in your OP, you said that the player "put 4000 in chips mistaking chips color". This is truly an unfortunate mistake on the player's part that has compounded the problem. I doubt anyone would have called the floor had the player made an uncommon declaration while putting out a single oversized chip of the wrong color. In that case, the TD might totally disregard the non-standard verbal and use #45-C to rule it as a silent single chip call. Given the color mistake, rule #45-D cannot be used to make this a call, if we simply disregard the verbal announcement. If we decide to ignore the declaration and allow the chips to speak we wind up with #46-A, a raise.
Rule #3 makes it very clear that it is the player's responsibility to make their intentions clear. This player failed to do so verbally and then exacerbated the problem with chips of the wrong color.
I wasn't at the table and do not know if there were other extenuating circumstances that led the other player(s) at the table to call the floor in what is almost always an intent to call. Had this player repeatedly made disputable acts with potentially nefarious intents?
What if it was the other way around? What if the TD talks to the player and he says: "I meant to say 'I raise.'." Would we still rule it a call? Do we trust in the player's unconventional verbal declaration or the chips regardless of color? Isn't it also the responsibility of the player to know the denomination of the chips? Perhaps we should at that to the ever growing list in Rule #2.
Regards,
B~